Rocket boosted automatic weapon and ammunition system

Sept. 7, 1965 κ. j. j. mcgowan 3,204,530

ROCKET BOOSTED AUTOMATIC WEAPON AND AMMUNITION SYSTEM

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Sept. 7, 1965 κ. j. j. mcgowan 3,204,530

ROCKET BOOSTED AUTOMATIC WEAPON AND AMMUNITION SYSTEM

Filed Oct. 15, 1963 ₈ Sheets-Sheet 2

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Sept. 7, 1965

Κ. J. J. MCGOWAN

3,204,530

ROCKET BOOSTED AUTOMATIC WEAPON AND AMMUNITION SYSTEM

Filed Oct. 15, 1963

Sheets-Sheet 3

Ι56_λ Ι55_)ΛΙ45 Ι56_χ Ι55_λ J45

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Sept. 7, 1965 κ. j. j. mcgowan 3,204,530

ROCKET BOOSTED AUTOMATIC WEAPON AND AMMUNITION SYSTEM

Filed Oct. 15, 1963 θ Sheets-Sheet 4

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Ό KENNETH J. J. McGOWAN

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Sept. 7, 1965 κ. j. j. mcgowan 3,204,530

ROCKET BOOSTED AUTOMATIC WEAPON AND AMMUNITION SYSTEM

Filed Oct. 15, 1963 8 Sheets-Sheet 5

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Sept. 7, 1965

K. J. J. MCGOWAN

3,204,530

ROCKET BOOSTED AUTOMATIC WEAPON AND AMMUNITION SYSTEM

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INVENTOR.

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KENNETH J. J. McGOWAN

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ATTORNEYS.

Sept. 7, 1965 κ. j. j. mcgowan 3,204,530

ROCKET BOOSTED AUTOMATIC WEAPON AND AMMUNITION SYSTEM

Filed Oct. 15, 1963 8 Sheets-Sheet 7

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INVENTOR.

KENNETH J. J. McGOWAN

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ATTORNEYS

Sept. 7, 1965 κ. j. j. mcgowan 3,204,530

ROCKET BOOSTED AUTOMATIC WEAPON AND AMMUNITION SYSTEM

Filed Oct. 15, 1963 g Sheets-Sheet 8

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INVENTOR.

KENNETH J. J. McGOWAN

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ATTORNEYS.

United States Patent Office

3,204,530

Patented Sept. 7, 1965 positive safety controls in that no force is exerted to arm the hammer linkage unless the bolt approaches battery and in that the hammer linkage is restrained against arming unless the bolt is locked;

Thirteenth—A compact rocket-launching weapon which requires the same order of space as the present .50 caliber machine gun;

Fourteenth—A relatively flashless, noiseless and smokeless weapon system, providing the individual combat infantryman with anti-tank assault capabilities; and

Fifteenth—A portable one-man automatic weapon system fully effective against armored vehicles at ranges in excess of one mile.

In considering the means by which these objects are sought to be attained, emphasis has, in the conception of the invention, been directed to the operating means or rod, the composite of the safety features, the ammunition, and the adaptation of the weapon features to the ammunition.

For a better understanding of the present invention together with other and further objects, advantages and capabilities thereof, reference is made to the following description of the accompanying drawings in which there is illustrated a complete weapons system employing an automatic weapon and ammunition in accordance with the present invention.

Description, of drawings

FIGS. 1A and IB together are a longitudinal sectional view of a preferred form of automatic weapon in accordance with the invention, taken along section line 1A—1A of FIG. 2 and looking in the direction of the arrows, the conditions being those which prevail when the weapon is set for semiautomatic fire and is ready to fire in response to a pull on the trigger, FIG. IB being a continuation of the right side of FIG. 1A so far as the weapon is concerned;

FIG. 2 is a longitudinal sectional view of said automatic weapon, generally as taken along the section line 2—2 of FIG. 1A, looking in the direction of the arrows, with certain parts shown in elevation and not in section for purposes of emphasis;

FIGS. 3 and 4 are, respectively, top and side views, with parts broken away for clarity in exposition, showing the conditions which prevail after a round has been fired and the operating rod and unlocked bolt have completely retracted;

FIGS. 5, 6, and 7 are fragmentary sectional views taken along the section lines 5—5, 6—6, and 7—7 of FIG. 3, in each case looking in the directions of the arrows, these figures emphasizing, respectively: the rocker arm; the end piece and bolt-unlocking yoke; and the composite of the rocker arm and the handgrip-operated lugs and arms;

FIGS. 8A and 9A, 8B and 9B, 8C and 9C are pairs of top and side views of the bolt lock and rocker arm release devices showing the positions of the parts under the following conditions, respectively: bolt not yet locked, bolt locked, and bolt being manually retracted from battery;

FIG. 10 is a fragmentary longitudinal sectional View of the weapon, as taken along the section line 10—10 of FIG. 6, emphasis being directed to the round-sensing pawl and is associated latch;

FIG. 11 is a pictorial outline or silhouette of said automatic weapon;

FIG. 12 is a side elevational view of the trigger, rocker arm, and hammer mechanisms under the conditions of semi-automatic fire, before the trigger is pulled, the upper hammer being safe;

FIG. 13 is a view generally similar to FIG. 12 but show-

3,204,530

ROCKET BOOSTED AUTOMATIC WEAPON AND AMMUNITION SYSTEM

Kenneth J. J. McGowan, Richmond, Ind., assignor to Avco Corporation, Richmond, Ind., a corporation of 5 Delaware

Filed Oct. 15, 1963, Ser. No. 316,224

Claims. (CI. 89—183)

The present invention is directed generally to ordnance and it resides in the field of automatic weapons systems. It is addressed more particularly to the provision of caseless, rocket-type ammunition and an automatic weapon for firing the same.

Ammunition for automatic weapons of the general type 15 under consideration has heretofore been characterized by the presence of a cartridge case, which presents numerous problems relating to the ejection of the case of a fired round and the feeding of a new round into the firing chamber. Such ammunition is further characterized by 20 problems of precision in manufacture and disposition of expended cases.

Problems pertaining to case ammunition have complicated the construction of automatic repeating weapons and required that the bolt action of gas-operated guns and 25 the like be controlled by complex offset cams and linkages displaced from the line of fire.

Prior art rocket launching devices are generally fired by electrical ignition.

The present invention constitutes a radical departure 30 from the three above-mentioned approaches, and is presented as a solution of the problems which they involve, in that the automatic weapon provided in accordance with the present invention percussively fires caseless rocket-type ammunition, and in that the bolt action of the weapon 33 is controlled by a simplified operating mechanism in the line of fire.

The objects of the present invention, not enumerated in the precise order of emphasis, are to provide:

First—A lightweight, portable, rapid-fire, artillery defense 40 system;

Second—A system particularly suitable for tactical operations in the field;

Third—A system including caseless percussion-fired rocket-type ammunition; 45

Fourth—A system featuring an automatic rocket-launching weapon having an unusually high ratio of fire power to weight;

Fifth—A shoulder-fired, low-recoil, automatic launcher;

Sixth—A launcher readily adapted to magazine or belt 50 feed and to mounted, dismounted or platform use;

Seventh—An automatic repeating weapon comprising a bolt, and operating means disposed directly behind the line of fire for the purpose of exercising control over bolt unlocking, bolt advancement and retraction; 55 Eighth—An automatic weapon characterized by a high firing rate, the bolt being retracted by the forces of a tension spring—i.e., by “pulling” action;

Ninth—An automatic weapon incorporating various safety features in addition to the usual manually operated 60 safety lever, such features including a mechanism assuring that the weapon cannot be fired unless the bolt is in battery position, and a mechanism assuring that the hammer cannot be armed unless the bolt is locked;

Tenth—A weapon including trigger and sear features pro- 65 viding a choice of automatic or semi-automatic fire;

Eleventh—A weapon which may readily be assembled and disassembled in the field;

Twelfth—A weapon which combines both passive and

3,204,530 ing the parts.in the positions assumed after the trigger has been pulled and at the instant of firing;

FIGS. 14 and 15 are side and end elevational views of the trigger and sear mechanism;

FIG. 16 is a longitudinal sectional view of the front buffer, taken along its central axis;·

FIGS. 17 and 18 are side and front views of the handgrip and slide subassembly;

FIG. 19 is a side view of a round of rocket ammunition in accordance with the system concepts of the invention;

FIG. 20 is an exploded perspective view of such round showing the parts disassembled; and

FIG. 21 is a longitudinal sectional view taken along the central axis of the round of ammunition of FIGS. 19 and 20.

Cycle of operation

The description at this point of a cycle of operation will facilitate understanding of the construction of the novel weapon. The assumed conditions are: First, semi-automatic fire; Second, a round in the chamber 20 (FIG. IB); Third, bolt groups 36 locked in battery position.

The parts referred to in this section of the specification are generally shown in FIGS. 1A, IB, and 2, but references to additional figures are made as necessary. The cycle of operation is as follows:

First—The upper sear 21 (see also FIGS. 12-15) is not engaging the rocker arm 22, but the rocker arm is held back (in its counterclockwise position) by the lower sear 23.

Second—The trigger 24 is pulled, and both sears 23 and 21 are urged, sear 23 turning slightly clockwise, freeing the rocker arm 22. .

Third—Spring-biased pusher 25 pushes the rocker arm 22 counterclockwise, and this motion is transmitted to upper' hammer 26, causing it to rotate counterclockwise and to strike lower hammer 27. '

Fourth—The lower hammer strikes the firing pin 28, causing the round 29 to fire.

Fifth—Gases flow rearwardly through ports 30 and 31, driving major piston 32 rearwardly, piston 32 driving minor piston 89 and operating rod group 33 rearwardly.

Sixth-—The annular flange 34 on the piston 32 strikes an nular shoulder 35 on the bolt group 36 so that the piston 32 is arrested, but the momentum of the operating rod group 33 is such that it continues to move rearwardly.

Seventh—As the operating rod 33 moves rearwardly, it stretches tension spring 37.

Eighth—The operating rod strikes yoke 38, and this motion is transmitted to bolt locks 39 and 40, unlocking the bolt group 36. The operating rod is latched in rearward position by two independent latches 41 (see also FIG.T0) and 42.

Ninth—The bolt group 36 flies back, retracted by the force of tension spring 37.

Tenth—As the bolt group retracts it resests the hammer linkage, lower hammer 27 striking upper hammer 26, causing rocker arm 22 to be rotated to its clockwise position.

Eleventh—If the trigger 24 is still being held back, upper sear 21 engages the rocker arm 22. If the trigger is not being held back, the lower sear 23 engages the rocker arm 22.

Twelfth—As the operating rod group 33 is retracted, it compressed spring 43.

Thirteenth—The bolt group so controls a spring-powered intermittent motion mechanism as to cause the magazine 44 to turn to align a fresh round of ammunition with the firing chamber 20, as soon as the rearward displacement of the bolt allows sufficient clearance. The magazine 44, bolt rack 45, housing 46 for the intermittant feed mechanism, spiral spring 47, spring-winding gear 48, driving member 49, and driven member 50 of this intermittent feed mechanism correspond in struc4 ture and function to the similarly named elements disclosed in my copending United States patent application entitled “Intermittent Feed Mechanism for HighInertia Load,” filed in the United States Patent Office on September 30, 1963. Serial No. 312,670, and assigned to the same assignee as the present application and invention. Said copending patent application is hereby incorporated herein by reference, and reference is made thereto for a full description of the construction and operation and interrelationships of the magazine here designated 44 and the intermittent feed mechanism here designated 51.

Fourteenth—The new round actuates the sensing pawl 167 and unlocks latch 41 (see also FIG. 10).

Fifteenth—The bolt group 36 unlocks latch 42.

Sixteenth—Now the bolt group reverses direction (see also FIGS. 3 and 4), driven forward by the operating rod group 33, which is driven by compressed spring 43. If for some reason no new round were in position, the latch 41 would not be opened and operating rod group 33 and bolt group 36 would remain in their rearward positions.

Seventeenth—As the bolt group 36 flies forward, it causes the magazine feed mechanism to be reset or readied for another feed operation.

Eighteenth—The bolt group 36 rams the fresh round into the firing chamber.

Nineteenth—The bolt group 36 is locked in battery position by bolt locks 39 and 40.

The firing of the first round of automatic fire corresponds generally to the first round of semi-automatic fire. In semi-automatic fire the upper sear 21 assures that the rocker arm 22 will be held in its clockwise position as the bolt group returns to battery, de-activating the upper hammer 26 so that the gun does not fire as the bolt group returns to battery. In automatic fire the rocker arm automatically so positions the upper hammer 26 that lower hammer 27 is impacted by upper hammer 26 and fires the weapon as the bolt group is locked in battery position. That is, plunger 25 automatically rearms the hammer 26 as the bolt group goes into battery— i.e., plunger 25 turns rocker arm 22 counterclockwise. This operation implies no restraint by the sears, and both sears 21 and 23 are “out of the way” of the rocker arm. Parenthetically, the invention includes another safety feature which requires that the bolt group be locked by locks 39 and 40 before rocker arm 22 moves counterclockwise, but this is discussed in detail later. Selector shaft 52 has been set for automatic fire, de-activating upper sear 21. The trigger is being held back, de-activating sear 23. Thus the gun fires as the bolt group returns to battery. The automatic fire cycle continues as long as ammunition is supplied and the trigger 24 is held back. . .

The above discussion assumes that the weapon has been set up for operation and provided with a full magazine. Suppose now that the weapon is being set up for firing, and that a full magazine is being supplied to it. Under those circumstances it is necessary to retract the bolt so that a round can be aligned with the firing chamber 20. This retraction of bolt 36 is accomplished by a handgrip mechanism 53 and immediately associated parts. Suffice it for the present to say that the handgrip is unlocked and manually pulled to the rear—i.e., toward the gunner. This manual operation draws rearwardly a slide 187, the function of which is two-fold: (1) to unlock the bolt locks 39 and 40; and (2) to retract the bolt group 36 rearwardly, the operating rod 33 then being engaged by latch 41 (see also FIG. 10) to lock the bolt group in its rearward position. It has already been stated that the bolt group opens latch 42 as it approaches the fully retracted position. Then the fresh magazine is put in place and a round aligned with the firing chamber. In order to. prevent the opening of latch 41 by the sensing of the presence of a round under these circumstances,

8,204,530 an independent manual control 95 for the latch 41 is provided in order to override the action of the sensing pawl·— that is to say, the control 95 can be set in such manner either as to permit or to prevent control of the latch 41 by the round-sensing pawl 167. Obviously when the magazine is being installed, control by the element 95 must be exercised as a safety feature.

The handgrip 53 is similarly retracted to extract a round from chamber 20 in the event of a misfire.

The bolt and operating rod groups

In the weapon in accordance with the invention, the bolt 36 (called “bolt group” because it comprises several interfitted components) performs these functions:

First, it chambers the ammunition (i.e., advances to ram the successive rounds of ammunition into the firing chamber 20);

Second, it provides, when locked, a closure (FIGS. 1A and 2) for the rear end of the firing chamber;

Third, it controls the magazine feed mechanism 51 in such a way that that mechanism feeds a fresh round as the bolt group completes retraction, the feed mechanism being readied for such operation as the bolt group advances into battery;

Fourth, it provides a housing for the piston 32 and is in concentric relation to the operating rod group, and in these and other respects the bolt feature of the present invention is radically different from the prior art;

Fifth, it provides means for manually extracting an unexpended round, when desired;

Sixth, it carries pusher means 25 which, on advance stroke, causes the hammer mechanism to be armed;

Seventh, it carries lower hammer 27 and firing pin 28 means, which cannot be actuated unless the bolt group advances into battery position; and

Eighth, on retract stroke it opens the operating rod latch 42.

The bolt group 36 (FIGS. IA and 2) comprises: the forward bolt member or bolt proper 55; the bolt extension 56; the operating rod guide tube 70; and the rack 45 (which controls the magazine feed mechanism). The rearwardly extending bore 66 in the bolt proper houses major piston 32.

The forward bolt member 55 is generally cylindrical in section. It comprises a solid face piece 57, axially bored at 58, annularly grooved at 59, 60, forwardly projecting to provide a mounting for an extractor 61, the latter being provided with a downwardly extending lip which slides forwardly over rim 62 of the round 29.

The bolt proper 55 is formed with an integral intermediate section 63 and an integral solid rear piece 64, formed with a rearwardly extending cylinder portion having a wall 65 and a bore 66. The bolt proper is formed with a vertically extending well 67, within which is mounted the crank-shaped lower hammer 27, the latter being rotatably mounted on a pivot 68. Laterally of the well 67 are formed in the bolt proper the axially extending gas ports 30 and 31. Within the forwardly extending bore 58 is a retainer 94, on which is slidably mounted the firing pin 28, normally biased rearwardly by a compression spring 69, seated in retainer 94.

The rear portion of bore 66 into the bolt extension 56 extends is enlarged to provide a shoulder-limited fit for the bolt extension.

The bolt extension 56 is a rearwardly extending tubular member formed as follows:

At its front, with a reduced portion which tightly and securely telescopes into the bolt proper 55;

Near its rear exterior, with an annular ring including locking shoulders 71 and 72;

With suitable outer diameter so that the annular ring slides within rear bolt guide 75, and the main portion of the bolt extension slides within forward bolt guide 74;

With a suitable inner diameter to slide over the cylindrical sleeve 76, which guides spring 43.

With a forwardly located annular interior shoulder 77 against the rear surface of which the front surface to flange 78 of operating rod guide tube 70 abuts;

And with a frontal face 35 which arrests travel of major piston 32.

The bolt extension 56 and the bolt proper 55 are suitabily shaped on the lower portions thereof to provide a longitudinally extending mounting for the bolt rack 45, which, as stated above, controls the intermittent feed mechanism 51 for the magazine. The rear of the bolt rack is formed with a downwardly extending lug 73 through which the pusher 25 slidably projects, the pusher being normally biased forwardly by a compression spring 119. The force of the spring 119 against the pusher is sufficient to turn rocker arm 22 counterclockwise unless the rocker arm is restrained.

Now, as to the operating rod guide 70, a part of the bolt group, it is cylindrical and hollow throughout, and is formed as follows:

With a rearwardly extending bore 79 for slidably receiving the long inner sleeve portion 83 of the operating rod group 33 and also the reduced portion of major piston 32, as well as minor piston 89;

With an enlarged exterior diameter portion 80, grooved to secure the forward end of tension spring 37;

With an annular flange 78, the front face of which abuts against the rear face of flange 77 of the bolt extension 56;

And with a forwardly extending section 81 terminating in alignment with shoulder 35.

It is now pointed out that the entire bolt group 36, comprising bolt proper 55, extractor 61, bolt extension 56, operating rod guide 70, and rack 45 is advanced and retracted as a unit, which is therefore referred to as the “bolt group.”

Referring now to the operating rod 33 (FIGS. IA and 2), its functions are:

First, to be retracted by gas-operated major piston 32 to strike yoke 38 and unlock the bolt group;

Second, to tension spring 37 and draw the unlocked bolt group back;

Third, to compress spring 43 to store power to drive the operating rod and bolt groups forwardly to battery position;

Fourth, to be held retracted by latch 41 (FIG. 10) and to hold the bolt retracted until a fresh round is in place; and

Fifth, to be held retracted by latch 42 until the bolt opens latch 42.

The operating rod group 33 comprises: an outer sleeve 82, enlarged forwardly securely to seat the front end of compression spring 43, and slidably mounted within bolt extension 56 with sufficient clearance to guide compression spring 43; a concentric inner sleeve 83, slidably mounted within operating rod guide portion 79; and a rear body portion 84, integral with sleeve 83. The body 84 has these formations:

An annular shoulder 85 for engagement with latches 41 and 42;

An annular ring portion 86 for securely fitting outer sleeve 82; and

A reduced frontal portion 87 providing security for the rear end of tension spring 37.

Note that a portion of tension spring 37 is in the circular space between element 82 of the operating rod group and element 70 of the bolt group. Also that a portion of compression spring 43 is in the circular space between element 82 and element 76. Also, the tension spring 37 is connected between the operating rod group 33 (at 87) and bolt group (at 80), and that the compression spring 43 is connected between the operating rod group (the enlarged front portion of 82) and the rear buffer 88.

The elements 82, 83, and 84 are parts of the operating

3,204,530 .

rod 33, and such parts are therefore referred to herein as the “operating rod group.”

Reference is now made to the gas-operated piston arrangement which drives the operating rod group to the rear when the weapon is fired. The chamber pressure increases, moves the round forwardly and outwardly, and the pressure is such that. gases escape rearwardly through the ports 30 and 31 and.drive the outer or major piston 32 rearwardly until flange 34 strikes shoulder 35. The outer piston impact and the continually escaping gases drive rearwardly a cylindrical inner minor piston 89, which is suitably grooved and ringed and provided with a connecting rod portion secured at 90 to the integral solid frontal portion of inner sleeve 83 of the operating rod 33.

It is reiterated that the piston 32 moves rearwardly relative to the bolt under the force of the gases mentioned above, until it strikes shoulder 35 of the bolt extension, whereupon the piston 89 and the operating rod continue to retract relative to the bolt. .

Note is now made of the fact that, at the time when the retracted operating rod group 33 is released by the opening of latches 41 and 42, so that the compression spring 43 drives the operating rod forward, the operating rod at the same time drives the bolt forward, the forward surface of the outer sleeve 82 of the operating rod group bearing against the rear surface of the flange 78 on the bolt guide 70. The point is that the bolt group and the operating rod group always advance together.

Secured to the forwardly extending boss of a stand member 91, fixed to the. end cap 92, is a forwardly extending tubular guide member 93 which fits into the interior bore of the operating, rod group 33 so that the operating rod group is guided thereby.

The trigger and hammer mechanisms

In the weapon in accordance with the invention it is essential to firing that the rocker arm 22 (FIG. 2) be placed in a counterclockwise position. When the rocker arm is in this position it causes the upper , hammer 26 to be positioned counterclockwise—-i.e., in an armed position. For reasons which will .be explained in a later portion of this specification, the rocker arm cannot be moved counterclockwise by pusher 25 unless the bolt locks 39 and 40 are locked.

Considering the second round of automatic fire, the pusher 25 positions rocker arm 22, when unrestrained, counterclockwise as the bolt group advances into and is locked in battery position, so that hammer 26 is also positioned counterclockwise and causes the weapon to fire as the bolt reaches battery_: position. As the bolt is retracted, the rocker arm 22 is moved clockwise as. lower hammer 27 strikes upper hammer 26. When termination . of automatic fire is desired, the trigger 24 is. released so that the rocker arm 22 engages the lower sear 23.

It will be noted that, during automatic fire, the selector lever 52 is so positioned as to lift or turn upper sear 21 slightly counterclockwise so that the upper sear cannot engage the rocker arm 22. On the. other hand, termination of semi-automatic fire is accomplished by upper sear 21, the selector lever 52 being positioned for semi-automatic fire to lower the end of upper sear 21. That is, the selector lever enables the upper sear for semi-automatic fire and disables it for automatic fire.

The discussion now proceeds to the details of the trigger and sears (as shown .in FIGS. 12-15 and FIG. 2), and particularly to the conditions pertaining to the initiation of firing.

Pivotally secured in relation to vertical lugs on a trigger housing 96, as by a pivot 97, are a trigger 24, a lower sear 23, and an upper sear 21. The trigger and the lower sear are biased into their normal positions, as shown in FIG. 12, by compression springs 98 and 99, respectively. The trigger and lower sear are so formed and arranged that, when the trigger is pulled (i.e., turned clockwise) against the force of compression spring 98, the lower sear is lowered, or turned clockwise, against the force of compression spring 99, disengaging the lower sear 23 from the rocker arm 22 and permitting the pressure of spring 119 (FIG. 2), acting on pusher 25, to turn rocker arm 22 counterclockwise (if the bolt group is locked).

Parenthetically, at this point it should be noted that during automatic fire, when the bolt advances, assuming the trigger to be still pulled, there is no sear restraint on rocker arm 22, and the force of pusher 25 is sufficient to position rocker arm 22 counterclockwise (if the bolt group is locked). On the other hand, if the trigger has been released during automatic fire, or if a round of semi-automatic fire has been ordered and fired, there will be sear restraint on rocker arm 22 when the bolt advances, and the rocker arm 22 will remain in clockwise position, the force of the pressure of spring 119 on pusher 25 not being adequate to overcome such restraint.

It will be observed that firing of this weapon is always initiated by removing the restraint of the lower sear 23 from the rocker arm 22.

During semi-automatic fire, if the trigger has been released after the firing of a single round, then the lower sear 23 will restrain the rocker arm. To assure such restraint and to conclude semi-automatic fire, whether or not the trigger has been released, there is provided the upper sear. 21. That is, if the trigger has not been released, the upper sear (surface 102) will hold the rocker arm portion 104 until the trigger is released, whereupon the lower sear (surface 101) holds the rocker arm at 104. The. upper and lower sears are coupled together by a tension spring 100, the function of which is to maintain in or close to abutment'the free ends of the two sears 21 and 23, except under those conditions when the setting of the selector lever 52 for automatic fire dictates that the upper sear 21 be'maintained in a counterclockwise position.

The selector lever 52 is a simple shaft with a flattened or semi-cylindrical section extending transversely of the upper sear. For automatic fire it is desired to position the upper sear 21 out of the way of the rocker arm latching section or bight 104. Accordingly, the selector shaft is turned so that its round surface cams the upper sear counterclockwise. For semi-automatic fire, on the other hand, the selector shaft 52 is so turned as to present its flat surface to upper sear 21, permitting the end of the upper sear to drop.

While both sears are urged, and sear 23 turns clockwise (FIG. 13) as the trigger 24 is pulled to initiate semi-automatic fire, so that the lower sear 23 releases the rocker arm 22, the upper sear does not under that circumstance restrain the rocker arm, the cam formations of the lower and upper sears, particularly their earn surfaces 101 and 102, respectively (the former being ahead of the latter), being such that the upper sear does not engage the rocker arm under that circumstance. The weapon is always initially fired from the lower sear 23.

The rocker arm 22 is formed with a rectangular aperture at 103 (FIGS. 5 and 13) to provide a latching section or bight 104, and it is this section with which the sears engage.

A safety lever 105 (FIG. 2), similar in construction to selector lever 52, is provided for the purpose of preventing any firing at all unless the operator affirmatively desires firing.. To this end a shaft 105, transverse to sear 23, is'formed with a flattened or semi-cylindrical section which can be turned to two positions: one (safe) in which the round surface locks lower sear 23 against any clockwise movement at all, thus locking the rocker arm 22 in clockwise position; the other position in which the flat surface of shaft 105 is turned toward lower sear 23, permitting free clockwise movement thereof.

The keystone of the arming and safety arrangements of this gun is the rocker arm 22. Emphasis is directed to the fact that, when the rocker arm is in its clockwise position, the gun is safe. When the rocker arm is pushed

3,204,530 counterclockwise, the weapon is fired (if the bolt group is in battery on semi-automatic fire, or when it comes into battery on automatic fire). A passive safety feature, therefore, resides in the fact that lower hammer 27 cannot be impacted unless the bolt group is in or finally going into battery position.

Another important safety feature of the weapon resides in the fact that, on automatic fire, the upper hammer 26 cannot be placed in firing or armed position unless the bolt group, when advancing, is locked in battery position. Let it be assumed that the bolt is traveling forward to the point where the shoulder portions 71 and 72 of the bolt group are pressing the bolt lock pieces 130 and 141 outwardly (FIGS. 8A, 9A). Under this condition the spring-biased plunger 25 tends to turn rocker arm 22 counterclockwise to place the upper hammer in firing position. Now this weapon is provided with an additional safety feature to assure that this counterclockwise turning action of the rocker arm 22 cannot occur until the bolt locking action is complete (i.e., until the locking pawls 141 and 130 swing inwardly again—see FIGS. 8B, 9B). In other words, a safety feature of this weapon resides in the fact that the upper hammer 26 cannot be placed in firing position until the advancing bolt is locked in battery. To this end (see FIGS. 1A and 5) there are provided two rocker arm release devices 106 and 107 (pivotally mounted on lug pairs

114-115 and 116-117 on the rocker arm), the function of which release devices is to sense that the bolt locking pawls have been pushed outwardly (FIGS. 8A, 9A) by ₃θ the forward-moving bolt, and to be restrained and in turn to restrain the rocker arm until those pawls swing inwardly (FIGS. 8B, 9B) to lock the bolt group. When the bolt group is locked, as it comes into battery, the locking pawls 141 and 130 are not in the path of the ends ₃₅of the release devices 106 and 107, and the rocker arm 22 is turned counterclockwise by pusher 25.

The rocker arm member 22 (FIGS. 2, 5, and 7) is a generally wishbone-shaped member formed as follows:

First, with generally vertically extending arms 108 40 and 109;

Second, with laterally extending and diametrically opposed integral bosses 110 and 111 bored to receive the stub shafts 112 and 113 on which the rocker arm is pivotally mounted; 45

Third, with a narrow bight portion 104 which constitutes the portion engageable with the sears;

Fourth, with a wider bight portion 122 formed with a central depression against which the pusher 25 abuts;

Fifth, with two pairs of rearwardly extending spaced 50 lugs 114-115 and 116-117, each pair being vertically bored to receive a pivot, such as the pivot 118, on which the rocker arm release device 107 is mounted—similarly, rocker arm release device 106 is pivotally mounted on pivot 135 between rearwardly extending lugs 114 and 55 115;

Sixth, with upwardly located apertures 120 and 121, providing the pivotal points to which the connector portions of the linkages which actuate the upper hammer are individually attached. 60

Now, as to the linkages which have just been mentioned, these include connectors 124 and 125 (FIGS. 2 and 5), utilized to control the hammer positioning. Connector 124 is pivoted at 121, and connector 125 is pivoted at 120. The forward ends of the connectors 124 65 and 125 are secured to the upper hammer yoke 126 by rods 198 and 199 (FIG. 3). The upper hammer yoke 126 is slidably mounted in such fashion that, when the weapon is armed, yoke 126 is in its rearward position, and when the weapon is not armed, it is in its forward 70 position. The hammer yoke 126 (FIG. 2) actuates upper hammer 26 through a link 127 in such manner that, when the rocker arm 22 is clockwise, the upper hammer 26 is in its unarmed, or upper, position. When the rocker arm js counterclockwise, the hammer 26 is in 75 its armed or lower position, whereat it strikes lower hammer 27. As has already been stated, the bolt retracts after firing, so that the lower hammer 27 strikes the upper hammer 26 and causes the rocker arm 22 to be restored to its clockwise position.

A comment on the composite of the various safety features is now in order. Note that no adequate force tends to move arm 22 counterclockwise unless the bolt group is in battery. This is a passive safety feature. Note further that the arm 22 is restrained against counterclockwise movement unless the bolt group is locked. This is an active safety feature. Note still further that the hammer 27 cannot strike the hammer 26 unless the bolt group is achieving battery position. It will be perceived that, in addition to the manual safety lever 105, ¹⁵ safety is assured by the composite of the three justmentioned features.

As to the firing mechanism, the lower hammer 27 is pivoted within the recess 67 (FIG. 2), the pivot being horizontal. The lower hammer 27, when it strikes the upper hammer 26, drives the firing pin 28 forwardly so that the round is percussively fired. The firing pin 28 is normally held in its rearward position by compression spring 69.

On semi-automatic fire, of course, the upper hammer 26 strikes the lower hammer 27 to drive firing pin 28 forwardly to fire the round.

Bolt locking and unlocking mechanisms

Reference is made to the bolt lock 40 illustrated in locking condition in FIGS. 8B and 9B, and in not-yetlocked condition in FIGS. 8A and 9A. It comprises a locking pawl 130 pivotally mounted at 131 at a point near its rear. Its swinging end is biased toward locking position by a compression spring 132. When the bolt group is locked, pawl 130 is in its counterclockwise, or inner, position (FIGS. 8B, 9B). Just before the bolt group is locked, during its forward travel, the bolt group shoulder 72 pushes pawl 130 into a clockwise position (FIGS. 8A, 9A). When in the latter position, a surface 133 on the free end of the pawl 130 has moved sufficiently outwardly of the bolt to be in the counterclockwise path of rocker arm release lever 107 (FIG. 9A), and it is this relationship which prevents rocker arm 22 from turning counterclockwise. On the other hand, when the bolt is locked (FIGS. 8B, 9B), the lug 133 on pawl 130 clears the free end of the rocker arm release member 107, so that the rocker arm 22 is free to be turned counterclockwise by pusher 25 (from the FIG. 9B position to the FIG. 9C position). A torsion spring 134 is mounted on the pivot 118 for the rocker arm release device in such manner as normally to urge the free end of that device inwardly, for a purpose which will be described later herein.

Parenthetically, it will be understood that the construction and operation of bolt locks 39 and 40 and rocker arm release devices 106 and 107 and their associated controlling linkages are similar, the bolt locks and rocker arm release devices being symmetrically constructed and arranged. Therefore, the detailed description of the bolt lock 40 and associated members need not be repeated with reference to bolt lock 39 and its associated parts.

Bolt lock 40 is released by a link 136 (FIG. 1A), pivotally secured to pawl 130 at 152, and the rear end of this link 136 is rigidly secured to a rod 137, which in turn is secured by a connector to the bolt-unlocking yoke 38. As previously indicated, it will be understood that rods 137 (for releasing 40) and 138 (for releasing 39) are identical and cooperate in performing the same function, these rods being secured to the bolt-unlocking yoke 38 at 139 and 140, respectively.

It has already been stated that, at the end of its rearward travel, the operating rod group 33, specifically portion 85 thereof, strikes the bolt-unlocking yoke 38, causing rods 137 and 138 to be drawn rearwardly, thereby

3,204,530

Π drawing the free ends of pawls 13® and 141 outwardly away from the bolt shoulders 72 and 71, respectively, thus unlocking the bolt group.

Now considering how the bolt group is locked, when the bolt advances into battery, its shoulder portions 71 and 72 simply slip under the free ends of the pawls 141 and 130, and, those ends being spring-biased, the pawls are pressed into engagement with the rear surfaces on shoulders 71 and 72, respectively, of the bolt. The rods 137 and 138 and bolt-unlocking yoke 38 are accordingly drawn forwardly as the bolt group is locked.

FIGS. 8C and 9C are discussed later herein, in the section relating to the handgrip.

The buffers

The forward buffer is designated generally in FIG. 2 by the reference numeral 174. This buffer is purely conventional and need not be described in detail. It decelerates the bolt and operating rod groups as they travel forwardly, and it is of the viscous type.

The forward buffer comprises an impact piston extension 155 (FIG. 2) which is slidably mounted and guided for translatofy motion along the top of portion 74 of the bolt guide. The arrangements are such that, as the bolt group comes forward, the upper arcuate portion of the enlarged ring portion 196 of the bolt group strikes the impact piston extension 155 and moves it forwardly. Shoulders 71 and 72 are formed in this annular ring portion 196.

Referring now to FIG. 16, the following actions then occur: The impact piston extension 155 moves rod 156 forwardly, and that rod in turn drives impact piston 157 forwardly within the oil compression chamber reservoir 158. Secured to the forward face of the impact piston 157 is a throttle needle which, as it moves forward, progressively narrows the oil flow aperture 160 on throttle plate 161. As oil flows from chamber 158 into chamber 162, it drives piston 163 forwardly against the force of return spring 164, disposed within the bleed chamber 165. The throttle plate is biased into its normal forward position by a compression spring 166.

Parenthetically, for purposes of convenience, the round-sensing pawl 167 is pivotally mounted on the bleed chamber housing 168. The bleed chamber is provided with a suitable cap 169, which is formed with a port at 170 to release the air compressed in buffing.

O-rings. are provided to seal surfaces against leakages, as shown, all in a conventional manner. The compression chamber reservoir is housed in cylinder 171, which is enlarged at its forward end to receive in oil-tight fit the rear end of bleed chamber housing 168.

When the bolt retracts, the rearward movement of piston 163 forces oil back into reservoir 158, forcing piston 157 rearwardly and driving the impact piston extension 155 back to its rearward position (FIG. 4).

The rear buffer 88 is a plastic plug (FIGS. 1A, 2, 3, and 4) generally cylindrical in shape and interiorly longitudinally bored. Near the fore portion the bore has an enlarged section to interfit with the spring guide 76, followed by a still more enlarged section terminating in a bevel so as to provide a complementary bumper surface for the enlarged ring portion 196 of the bolt group. The rear buffer aids in arresting the rearward movement of the bolt group and absorbs the shock incident to the arrest of the bolt group.

The housing and frame

Before concluding this specification with a description of the operating rod latches 41 and 42, magazine replacement, extraction, and handgrip retraction of the bolt, it is in order to discuss briefly the housing and frame arrangements.

The housing is formed at the rear with a suitable butt stock 128 (FIG. 11), and at the front with a grasp handle 129. The rear of the housing for the operating parts is closed by a generally circular rear cap member 92 (FIG. 1A), countersunk on its forward face to provide a recess for a wafer-shaped shock absorber 144. Secured on the forward face of this wafer 144 is the stand member 91 which supports the inner tubular guide 93 for the operating rod group. Positioned forwardly of the wide flanged portion of stand 91 is the end piece 142, best illustrated in FIGS. 1A and 6. This end piece is circular but is formed with a generally cruciform cutout to provide room for the bolt unlocking yoke 38 and other parts presently described. The main portion of the housing comprises a generally tubular cylindrical jacket 145 which is provided with windows on each, side, those windows providing access to the bolt locks and being closed by plates 146 and 147 (FIG. 3) screwed onto cylinder 145. Cylinder 145 terminates adjacent a forward transverse partition 148, to the upper edge of which is secured a semi-cylindrical hood 149. The latter serves as a top cover for the magazine, and it terminates adjacent a front cap 15® which is bored and provided with suitable fittings to secure the removable barrel 151 (FIG. 11), the latter being screw-threaded at its rear exterior for that purpose.

The rear cap 92 and rear end piece 142 and the cylinder 145 are cut out at the bottom to provide room and security for channel members 153 and 154 (FIGS. 6 and 11), the purposes of which will be discussed in connection with the description of the handgrip 53.

As best seen in FIGS. 11, 4, and 2, the cylinder 145 is further formed, immediately aft of partition 148, with a pair of laterally extending lugs (see element 172), only one of which is illustrated, to which lugs the housing 46 for the intermittent feed mechanism for the magazine is bolted. One of these lugs is on each side of the cylinder.

The magazine 44 is mounted between shaft 49 and pin 173 (FIG. 2). Pin 173 is slidably secured within a retainer 175. The retainer is fitted with a screw 176 which projects into a groove formed in pin 173. When the magazine is in place, screw 176 projects into forward transverse portion 177 of this groove. When the operator desires to remove the magazine, he turns pin 173 counterclockwise, retracts pin 173 away from the magazine by approximately the length of longitudinal groove portion 178, and then turns pin 173 counterclockwise so that screw 176 fits into the rear groove portion 179. The pin is turned as by a manually operable crank handle 180. When the pin 173 is retracted, as aforesaid, the magazine 44 is simply removed from shaft 49 and pin 173, and a new full magazine is installed, whereupon, by reverse manipulation of crank handle 180, the pin 173 is pushed toward the new magazine and the new magazine is locked into place.

The operating rod latches

The round-sensing pawl 167 (FIGS. 10 and 16) is pivotally mounted with reference to housing 168 of the forward buffer 174, this being simply a convenient location. It displaces a rod 181 (FIG. 10), which in turn positions the pivotally mounted pawl 182 of latch 41 in such a manner that when a round is in position, ready to be chambered by the forward movement of the bolt group, the operating rod is unlatched. However, when there is no round in this position, ready to be rammed into battery, then the linkage 167, 181, 182 operates in such a manner that the operating rod is latched to the rear, pawl 182 locking with portion 85 of the operating rod for that purpose.

The action of the sensing pawl may be overridden, if desired, by manual control 95, the function of which is to grip the rod 181 and position the latching mechanism 41 to hold the operating rod in retracted position even though there is a new round in the chamber.

The other operating rod latch 42 comprises a pawl

184 (FIG. 2) pivotally mounted in a recess formed in the rear buffer 88, and this pawl is normally biased into latch3,204,530 ing position by a compression spring 185. This latch is so constructed and arranged as to engage and hold the operating rod (at 85), and to hold the operating rod until the bolt flies rearwardly and disengages pawl 184 from portion 85 of the operating rod. The bolt accomplishes this by pushing pin 143 (FIG. 1A) to the rear, turning arm 194 on pawl 184 counterclockwise (FIG. 2).

The handgrip subassembly

The handgrip comprises a downwardly projecting, manually manipulable handle 186 which is secured to a horizontally extending slide or carriage member 187 (FIGS. 2, 17, 18). The slide member is adapted to slide within the channel members 153 and 154 (see also FIG. 6) on track formations 188. A conventional catch 189 locks the handgrip mechanism in its forward position, and the catch is released to permit retraction of the handgrip mechanism. Wheels 193 are mounted on each side of the rear of the carriage 187 to facilitate its translatory motion.

The purpose of the carriage member 187 is to withdraw the bolt to the rear. Accordingly, there is attached to the slide a bolt-withdrawal yoke device comprising a pair of forwardly and upwardly extending arms 190 and 191, so spaced and located (slightly in front of lateral projections on member 73 when the bolt is in battery) that they can be moved rearwardly to engage with the front of said lateral projections (FIGS. 7, 17 and 18) on the bolt. As the handgrip is drawn to the rear, after sufficient motion of the slide member or carriage 187 to unlock the bolt locks, these arms 190 and 191 draw the bolt group and operating rod group to the rear.

Also attached to the carriage 187, to the rear of the bolt-engaging portions of arms 190 and 191, are a pair of vertically and outwardly extending arms 54 and 192, triangularly cam-surfaced at their tops to strike similar cam surfaces on pawls 130 and 141 and to cam outwardly the pawls 130 and 141, therefore unlocking the bolt group. Note the triangular cam surfaces at the top of 54 and on the inner under surface of locking pawl 130 (FIGS. 8A,8B,8C).

Before discussing further handgrip retraction action, let the bolt lock construction be further considered.

FIGS. 8A and 9A show the bolt group advancing forwardly but not far enough to be locked. The bolt lock pawl 130 is thus cammed out by shoulder 72 and prevents counterclockwise motion of the rocker arm release device 107, because the bolt lock pawl 130 rides under the rocker arm release 107. Note that the compression spring 119 which offers the motive power for the rocker arm’s rotation is only partly compressed. When the bolt group advances further and is locked, locking pawl 130 swings inwardly and the rocker arm 22 swings counterclockwise, the free end of release device 107 dropping below the plane of the top surface of pawl 130 (i.e., from the FIG. 9B to the FIG. 9C position).

FIGS. 8C and 9C show the rocker arm 22 after a round has been fired. If a misfire occurs, there is no automatic impact of lower hammer 27 against upper hammer 26 to bring the rocker arm back toward its clockwise position as in FIGS. 8A and 9A. In order to manually open the bolt, the handgrip 53 is pulled to the rear, as has been stated. This causes the arms 54 and 192 to cam the boltlocking pawls 130 and 141 out, thereby releasing the bolt. Again considering FIGS. 8C and 9C, it is necessary for the rocker arm releases 106 and 107 to be able to swing outward as the bolt-locking pawls swing outwardly. Therefore, they are pivoted at 135 and 118 and spring-loaded toward their normal inner positions. They are constructed in such a way that they cannot swing inward any more than the position shown in FIGS. 8B and 9B. They are free to move outward (against bias), but not inward.

Referring further to the catch for the hindgrip, reference is made to FIG. 18. The catch comprises a trans verse slide member 224 which is formed with upstanding lugs 225 and 226. When the handgrip assembly is in its normal forward position, the lugs 225 and 226 engage notches on the underside of the members 153 and 154. For example, referring to FIGS. 11 and 18, the lug 225 engages the notch 227 when the handgrip is in its normal forward position. On the other hand, when the handgrip is retracted, the lug 225 engages the notch 228 (FIG. 11). Lug 226 similarly engages with notches (not shown) on member 153.

The transverse slide member 224 is spring-biased into its normal central position by a central barrier 229 and compression springs as shown in FIG. 18. The slide 224 is manually movable to either side, for purposes of disengaging the handgrip assembly from the members 153 and 154, by spring-retaining buttons 230 and 231.

Ammunition

Referring now to FIGS. 19, 20, and 21, there is shown a round of ammunition 29 provided in accordance with the present invention and suitable for use with the weapon fully described above and also so provided. The ammunition here disclosed for purposes of illustration is 40 millimeters in diameter, approximately 8 inches long, weighing 0.86 pound. It is powered by a solid propellant starshaped grain approximately 70 grams in weight. It is spin stabilized and reaches a peak velocity at burn-out on the order of 1500 feet per second.

Basically the round here shown has four phases of operation during firing and flight toward a target:

^;(1) Ignition;

(2) Acceleration in the barrel 151;

(3) Acceleration to peak velocity outside the barrel; and (4) Free flight following burn-out of the propellant.

The ammunition comprises the following principal parts mechanically coupled in cascade, from rear to front: igniter 200, rocket motor 201, baffle 202, adapter ring 203, war head 204, fuze 205, all generally cylindrical in contour, and ogival cap 206.

The igniter is of the percussion type. It comprises a primer 207, a metallic baffle member 208 formed with ports, and a body 209, the latter being suitably bored to provide a stem 210. It will be understood that in firing, the firing pin strikes the primer 207, igniting it by percussion; the primer projects a flame which causes ignition of of a charge in the bore 201; and the ignition train then ignites the rocket propellant 213; resulting in the generation of propellant gases which accelerate the rocket outwardly through the barrel and then in flight.

An igniter suitable for use in this ammunition is shown in the' copending patent application of Anthony C. DeMatthew, Serial No. 248,564, filed in the United States Patent Office on December 31, 1962, entitled “Simplified Rocket Propellant Charge Igniter,” and assigned to the same assignee as the present application and invention. A nozzle insert 211 is inserted in the rearwardly extending boss 222 provided on the rocket motor body 201. The rocket motor body 201 is hollow and cylindrical in contour and is provided on its fore portion with a screwthreaded extension 212. A star-shaped propellant grain 213 is placed within the rocket motor body.

The rocket motor body and the war head are connected by an adapter ring or bulkhead 203, the latter being interiorly threaded to fit the rocket motor body 201 and the war head 204 and being provided with an annular shoulder, the rear surface of which supports the main baffle member 202. The baffle member 202 has transverse ports 214 which permit gases to escape from the rocket motor through angled transverse ports 215 and 216 formed in the adapter ring for purposes of spin stabilization.

The cylindrical war head 204 is provided with a threaded reduced portion at its rear and is accordingly screwed into the adapter ring 203. The ogive 206 is of

3,204,530 the conventional bluntly frontally pointed formation, and it is press-fitted onto a dummy fuze 205. The dummy fuze is screw-threaded at 217 into the fore part of the war head, such fore part being interiorly bored to receive the rearwardly .projecting parts of the. dummy fuze. It will be understood that the dummy fuze and the war head here shown may be replaced by any suitable timedelay fuze and war head for anti-personnel, anti-tank, incendiary, tracer, or pyrotechnic tasks.

Now going through a cycle of operation of the am-, munition, the primer 207 is struck by the firing pin 28 (FIGS. 13, 19-21), hot gases from the· primer, pass through baffle 208, and they ignite a boron potassium nitrate ignition mix, for example, in stem 210. -The burning ignition mix passes into the rocket motor chamber and starts the surface of propellant 213 burning; Gases generated by the burning propellant build up pressure. When sufficient pressure is achieved, the shear pins 218 and 219, holding the igniter housing 209 to ;the rocket motor body, are broken and the housing is. excelled rearwardly.

At this point the throat of nozzle insert 211 is fully opened, and the rocket motor beings to initiate flight. While the gases build up pressure in the . rocket chamber, the gases are also passed through the strainer 202 into the spin jets 215 and 216, so that the: round is caused to rotate rapidly around its axis, or to spin. Initial/spin sufficient to stabilize the round at launching is achieved by reason of standard rifling in the’barrel : 151 and the use of rotating bands such as 221 on the round.

In considering the relationship of the ammunition to the operation of the gun, let it be observed: that the gases expelled from the nozzle 211 build up.pressure in the firing chamber 20. This pressure build-up continues until the round moves outwardly in the barrel, at which time, chamber pressure decreases. Simultaneous with the pressure build-up in the firing chamber, gases are passed through the ports 30, 31 on the: face of the bolt (FIG. IA), impelling piston 32 backwards and forcing. the operating rod group 33 rearwardly. This action begins immediately, so that energy for feeding the next round is stored before the fired round leaves the barrel.

Conclusion

An additional word with reference to FIGS. 3 and 4 may be helpful at this point. FIG. 3 shows the condition of the operating parts after the trigger has been pulled and semi-automatic fire has occurred. The bolt has been unlocked and is in its fully retracted position. In FIG. 4 the bolt is fully retracted and has unlatched latch 42, freeing the operating rod group.

While the specific embodiment of weapon in accordance with the invention and herein shown is a 40 millimeter portable weapon which approximates 15 pounds in weight unloaded and 23 pounds fully loaded with ah eight-round magazine, it will be understood that, the invention is applicable to other calibers of ammunition and to tactical warfare on land, sea, or in the air. The embodiment herein shown is accordingly presented by way of illustration and not of limitation. In the specific embodiment, the rear buffer 88 and the shock absorber 144 are made of a suitable plastic, such as Delrin; aluminum is used for the housing generally, and liberally among the moving parts. Many of the moving and operating parts are preferably constructed of steel. The selection of appropriate materials is well within the capability of those of ordinary skill in the art, with the disclosure before them.

While there has been shown and described what is at present considered to be the preferred embodiment of the invention, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the proper scope of the invention as defined in the appended claims. Accordingly, it is intended ip such claims to cover all modifica tions and changes as fall within the scope of the invention there defined.