Projectile for a muzzle loading rifle-bore mortar

United States Patent uu 3,613,596

<td> [72]</td><td> Inventor</td><td> Erik Walde Eskilstuna, Sweden</td>

<td> [21]</td><td> Appl. No.</td><td> 820,567</td>

<td> [22]</td><td> Filed</td><td> Apr. 30,1969</td>

<td> [45]</td><td> Patented</td><td> Oct. 19,1971</td>

<td> [73]</td><td> Assignee</td><td> Forsvarets Fabriksverk Eskilstuna, Sweden</td>

[56] References Cited

UNITED STATES PATENTS

34,493 2/1962 Havens......................... 102/94

2,325,560 7/1943 Wauters....................... 102/49.2 X

3,023,704 3/1962 Dawson etal................ 102/94

3,143,074 8/1964 Jasse............................ 102/94

Primary Examiner— Robert F. Stahl Attorney—Eric Y. Munson

[54] PROJECTILE FOR A MUZZLE LOADING RIFLEBORE MORTAR

S Claims, 7 Drawing Figs.

[52] U.S.C1........................................................ 102/94,

102/49.1

[51] Int.Cl.........................................................F42b 31/00,

F42b 13/22

[50] Field of Search............................................ 102/93,94,

49.1,49.2

ABSTRACT: A projectile for a muzzle loading rifle-bore mortar, with the projectile having an annular, circumferential groove provided with a rifled surface; an angularly split ring is located in the groove and is of less width than the groove so that the ring can move within the groove. The ring has resiliency sufficient to permit it to expand to a diameter similar to the diameter of a rearward nonrifled area of the mortar barrel and the said nonrifled part of the barrel has a diameter similar to that of the bases of the rifling. The depth of the groove increases steadily from the rearmost to the foremost of its flank surfaces.

<img file="US3613596A_D0001.tif" />

PATENTED oct 191971

3,613,596

SHEET 1 CF 2

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<img file="US3613596A_D0004.tif" />

INVENTOR.

PATENTED oct 191971

3,613,596

SHEET 2 CF 2

15

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<img file="US3613596A_D0007.tif" />

Fig 5

15 4 17 3 11 6

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<img file="US3613596A_D0009.tif" />

INVENTOR.

3,613,596

PROJECTILE FOR A MUZZLE LOADING RIFLE-BORE MORTAR

This invention relates to a projectile intended to be fired from a muzzle loading rifle-bore mortar.

It has previously been proposed to provide a projectile having a resilient driving band and intended to be fired from a muzzle loading rifled-bore mortar. In this case the projectile has a driving band that is movable in a groove fraying a width considerably greater than the width of the driving band. The groove has a forwardly decreasing depth. The driving band does not interfere with the dropping of the projectile into the barrel of the mortar by gravity when loading, as the driving band is located in the rear part of the groove. At the firing of the projectile, engagement with the rifling is insured by the driving band which is pressed forwardly by the pressure of the gases and increases in diameter.

The pressure of the gases in a mortar is not constant, as the propellant charge is varied in order to obtain different velocities. Thus, it is unsuitable to use the pressure of the gases to bring the driving band into engagement with the rifling.

According to the present invention the driving band is brought into engagement with the rifling without making use of the pressure of the: gases. This is accomplished by the present invention in which the groove has a forwardly.continuously increasing depth and the driving band is obliquely split and has a resiliency sufficient to permit a radial expansion of said band to a diameter that corresponds to the diameter of a rearwardly located nonrifled part of the barrel of the mortar, which part has the same diameter as the bottoms or bases of , the rifling.

Reference is to be had to the accompanying drawings in which an illustrative embodiment of the invention is shown and in which,

FIG. 1 is a view partly in section and partly in elevation of the projectile and a part of the barrel of the mortar;

FIG. 2 is a sectional view of the driving band and a part of the projectile, and

FIGS. 3 to 7 are sectional views of portions of the driving band, a part of the projectile and a part of the barrel of the mortar and showing the Operation of the disclosed construction.

According to FIG. 1, a projectile 1 is shown as being located in the barrel of a rifle-bore mortar. The projectile has an annular circumferential groove 2 containing a driving band 3. The width of the groove is considerably greater than the width of the driving band so that the band is capable of movement in the groove. The groove has a forwardly continuously increasing depth, that is, the bottom surface of the groove is the mantle surface of a truncated cone. The bottom surface of the 50 groove 2 has rifles 4 extending parallel to the generatrix of the mantle surface. The depth pf the rifles 4 is directly proportional to the diameter of the groove with zero-depth at the smallest diameter of the groove as will be noted in FIGS. 2 and 3.

The driving band 3 is obliquely or angularly split as shown at 7 in FIG. 1 and has a resiliency sufficient to permit radial expansion of the band to cause it to assume a diameter corresponding to the diameter of a rearwardly located nonrifled part of the barrel, which nonrifled part has substantially the 60 same diameter as the bottoms of the rifling.

The cross-sectional shape of the driving band 3 is illustrated in FIG. 2. The cross-sectional shape is in the form of a parallel trapezoid having a beveled outer surface 8 and a rounded surface at 9. The parallel sides or ends of the trapezoid are the 65 two flank surfaces 10 and 11. The surface 12 which is that which is brought into engagement with the rifling of the barrel is perpendicular to the two flank surfaces. Between the outer surface 12 of the band and the rear flank surface 11 is the beveled surface 8. The remaining inner surface 13 is disposed 70 parallel to the bottom of the rifles in the groove. The driving band is preferably made of copper or of some other suitable material.

The details of the barrel are illustrated in FIGS. 1 and 3. The muzzle 14 of the barrel is conical as shown in FIG. 3. The 75 greatest diameter of the same is slightly greater than the diameter at the bottoms of the rifling. The smallest diameter is the same as the diameter of the barrel. The barrel has rifles 15 made in the conventional manner with right-hand or left-hand twist. The area rearwardly of the rifles 15 is the loading room or chamber 16, which is nonrifled and has the same diameter as the bottoms of the rifling. The transition 17 (FIG. 1 and 5) between the rifles and the loading room is conical Le., the lower ends of the rifles 15 are beveled. The projectile is provided with a holder 18 for the propellant charge.

The operation of the device according to the invention will be described with reference to FIGS. 3 to 7.

The projectile is inserted in the muzzle of the barrel as: in FIG. 3. When the beveled surface 8 Of the driving band 3 contacts the conical muzzle 14, the resilient driving band is compressed and is thus given the same diameter as the internal diameter of the barrel. The projectile will then slide down into the barrel by gravity exerted by its weight (FIG; 4). The air in the barrel between the projectile and the bottom of the barrel is evacuated through the rifling 15 of the barrel.

When the projectile reaches the end of its travel or the point shown in FIG. 5, the holder for the propellant charge wilfcontact the firing pin at the bottom of the barrel. The resilient driving band will expand to a diameter corresponding to the diameter of the rearwardly nonrifled part of the barrel, which part has the same diameter as the bottoms of the rifting. At the same time, the driving band will slide rearwardly in the groove 2 owing to the inertia of the driving band, when the downward movement of the projectile is abruptly stopped.

The principle of operation at firing is illustrated in FIGS. 6 and 7. When the projectile begins to advance in the barrel under the propelling action of the gases, the driving band will be located between the transition 17 (between the rifles 15 of the barrel and the loading room 16) and the rifles 4 on the bottom surface of the groove. When the projectile moves further forwardly the driving band will be brought into engagement with the rifles 15 of the barrel and the driving band will be moved rearwardly in the groove to a position, in which the rear flank surface 11 of the driving band will contact the rear flank surface 6 of the groove. When the’projectile advances in the barrel, the projectile is then caused to rotate by the twisted rifles of the barrel.