Trigger mechanism

July 15, 1941.

J. B. SMITH

TRIGGER MECHANISM

Filed April 19, 1937

2,249,231

Sheets-Sheet 1

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H/5 ATTORNEY

July 15, 1941.

J. B. SMITH TRIGGER MECHANISM Filed April 19, 1937

2,249,231

Sheets-Sheet 2

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INVENTOR JOHN. B. -5M/TH

BY

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H/S ATTORNEY

Patented July 15,1941

2,249,231

UNITED STATES PATENT OFFICE

2,248,231 TRIGGER MECHANISM John B. SmHia, Oakland, Calif. Application April 19, 1937, Serial No. 137,783

Claims.

My Invention relates to mechanism for releasing a cocked element of a gun and the broad object of the invention is to provide an improved construction and arrangement of the trigger release elements.

Another object of my invention is to provide a trigger mechanism having means for holding an element in cocked position without interfering with the trigger movement, so that the element may be released by delicate movement of the trigger. This feature also allows the trigger to hold its adjustment.

Other objects of the invention include the provision of means for adjusting the trigger poundage, and of means for adjusting the trigger pull and backlash movements.

A further object of my invention is to provide a trigger mechanism which is self-contained in a housing, mounted for detachment as a unit on the gun; and in which adjustments may be made from outside the housing without disassembling the housing or removing it from the gun.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following description of my invention. It is to be understood that I do not limit myself to this disclosure of species of my invention, as I may adopt variant embodiments thereof within the scope of the claims.

Referring to the drawings:

Figure 1 is a side view, partly in section and partly in elevation, showing my trigger mechanism mounted in a bolt action rifle. The section is taken just behind the cover plate of the housing which encloses my mechanism to show the internal parts; and the gun is shown with unshaded lines to distinguish it from my improvements. The parts in this view are in cocked position.

Figure 2 is a similar view of the trigger mechanism, separate from the gun, and showing the parts in uncocked position.

Figure 3 is a side view of the mechanism on' somewhat larger scale and apart from its housing, showing the construction of and relationship between the parts.

Figure 4 is a similar view showing a modified construction; and

Figure 5 is another similar view of a modification adapted to a hammer gun.

In terms of broad inclusion, the trigger mechanism embodying my invention comprises a toggle for holding an element in cocked position, and a trigger for controlling movement of the toggle. The toggle arms are arranged to direct (01.42—88) the major portion of the firing pin thrust against a fixed pivot, and are adapted to rotate about their elbow pivot to release the cocked element.

Suitable springs are provided for resetting the parts after the trigger is pulled; and means are provided for adjusting the poundage pull necessary on the trigger to release the cocked element. Means are also provided for adjusting the trigger pull and backlash movements. The mechanism is preferably mounted as a unit in a housing, and means are provided for detachably mounting the housing on a gun. Preferably the adjusting screws are accessible for adjustment from outside the housing, so that the trigger poundage and pull may be changed without dismantling the gun.

In greater detail, and referring particularly to Figure 1, the trigger mechanism of my invention comprises a relatively flat housing 2 designed to fit into the stock of a gun. For purposes of illustration, I have shown my improved trigger mechanism in conjunction with a standard bolt action rifle, but it is understood that the mechanism may be used with other types of guns. It is also understood that the trigger mechanism may either be built directly into a gun when it is manufactured, or supplied as a separate unit adapted for Installation into a gun originally having another and less desirable type of trigger mechanism.

The standards parts of a bolt-action rifle are illustrated by unshaded lines to distinguish them from my improvements, and comprise a stock 3 having a recess 4 for receiving the housing 2 of my unit. A bolt receiver 6 is mounted on the stock by suitable studs Ί which also serve to fasten the trigger guard 8. A barrel 9 is threaded into the forward end of the receiver; and a bolt i i is slidably mounted in the receiver for loading cartridges from a clip 12 into the barrel. The bolt encloses a firing pin i 3 having a cylindrical portion 14 terminating in a cocking piece 15.

Cylindrical portion 14 of the firing pin encases a main spring 16, compressed between the firing pin and a suitable stop provided in the bolt, so that the pin is urged ahead. The cylindrical portion of the pin has a slot 17, and a part of the cylindrical wall behind this slot provides a lug 18 for engaging the trigger mechanism when the gun is cocked. The firing pin is cocked automatically when the bolt is pushed ahead, by reason of the pin being held by the trigger mechanism during the final portion of the bolt closing movement. During compression of spring 16 bolt handle 19 is rotated down against a cam sur65

2,2 face to facilitate closing the bolt and also to lock it. These parts and movements are common to standard bolt-action rifles, as will be readily perceived.

Housing 2 of my improved trigger mechanism is preferably made from a block of steel milled to provide suitable recesses for receiving the working parts, and is covered by a plate (not shown) which is secured by screws 20 threaded into the body portion of the housing. The housing is shaped to position its lower face flush with the underside of stock 3 inside trigger guard 8, with the upper portions of the housing projecting into the usual receiver slot 21 below the firing pin.

Means are provided for detachably mounting housing 2 on the receiver, and to permit lowering the housing for extracting the bolt. For this purpose a pin 22 is provided in the receiver, extending through the upper forward portion of the housing. The housing is accurately positioned by a stop 23 on the housing adjacent one side of pin 22 and abutting the receiver. A releasable stop or screw 24 threaded through the housing and abutting the receiver adjacent the other side of pin 22, serves to lock the housing in position. Screw 24 extends down through a slot 26 in the stock, so that the head of the screw lies outside. By this arrangement screw 24 may be backed off, allowing the housing to swing down through a slot 25 in the trigger guard to free the firing pin from the trigger mechanism. Bolt i I may then be withdrawn entirely from the receiver, which is desirable for purposes of cleaning and repair.

The working parts of my trigger mechanism comprise a toggle sear having a pair of arms 21 and 28 pivotally connected by an elbow pin 29. Arm 21 of the sear has a fixed pivot provided by a pin 31 pressed into the arm and journaled in the housing; and arm 28 has a floating pivot provided by a pin 32 pressed into the housing and engaging an arcuate slot 33 in the arm. Arm 28 also has a lug portion 34 projecting upwardly through an opening 35 in the bolt and engaging the firing pin lug 18 to hold the pin in cocked position. Sear lug 34 has a concave groove along its upper edge, in which the arcuate lug 18 may slide when the firing pin moves ahead.

As best shown in Figure 3, arms 21 and 28 of the toggle sear are arranged with the elbow pin 29 of the sear interposed between the point of engagement with the firing pin and the fixed pivot 31, so that the major portion of the firing pin thrust is directed along the arms and against fixed pivot 31. The arms are stabilized, yet permitted a limited degree of rotation about their elbow pivot 29, by the floating pivot 32—33; guide slot 33 of which extends along a line passing through pin 32 and a point between elbow pin 29 and the point of contact with the firing pin. The sear is urged upwardly into engagement with the firing pin by a sear spring 36 compressed between the housing and sear arm 21.

In order to release the firing pin a component of the main spring thrust is directed downwardly against the sear, tending to cause rotation of the arms about their elbow pin. This is accomplished by providing an inclined cam surface 31 on lug 34, engaging a complementary sloping surface on the firing pin lug 18. I have found that a flat cam surface inclined about 30° from the vertical gives good results. With such a cam surface a line passing through the centers of elbow pivot 29 and fixed pivot 31 lies about 30°

19,231 from the horizontal to make it substantially perpendicular to the cam surface when the parts are cocked, so as to direct the major portion of the thrust against the fixed pivot.

In this arrangement pin 32 of the floating pivot lies directly below the point of engagement with the firing pin; and the axis of slot 33 makes an angle of about 45° with the vertical when the parts are cocked. This positions pins 29, 31 10 and 32 in triangular formation, with the floating pivot pin 32 and fixed pivot 31 lying below elbow pin 29, and the latter arrangedbetween the fixed pivot and the point of sear engagement.· By so positioning the parts, a relatively small compo15 nent of the main spring thrust tends to cause rotation of the sear arms downwardly about the elbow pivot to release the firing pin.

Trigger means are provided for holding the toggle sear against the force tending to release 20 the firing pin. For this purpose a trigger controlled element or pawl 38 is provided for supporting the sear. This member is pivoted at its lower end by a pin 39 and has a smooth upper surface slidably engaging under a similar sur25 face on the underside of sear arm 21. The sear is therefore held until release point 41 on the pawl is pulled back past release point 42 of the sear. The release points are preferably located directly below elbow pin 29.

Pawl 38 is moved by a trigger 43 pivotally mounted on the housing by a pin 44 and having a pair of oppositely extending arms 46 and 41. Arm 46 of the trigger engages a lip 48 on pawl 38, and operates to rotate the pawl out of en35 gagement with the sear when the trigger is pulled. A light spring 49 between the pawl and trigger arm operates to keep these elements separated, and a second spring 51 under the arm keeps the trigger forward. The combination of 40 springs 49 and 51 largely determines the poundage pull on the trigger necessary to release the firing pin, since the effect of the main spring on the trigger is negligible by reason of the light pressure exerted on pawl 38 by the sear. In 45 order to adjust this poundage a plug screw 52 is threaded into the housing behind spring 51; this adjusting screw being accessible from the exposed lower side of the housing. I have made adjustments over a range of from two to ten pounds on the trigger with my mechanism.

In order to adjustably limit the draw and back lash movements of the trigger, a pair of screws 53 and 54 are threaded into the housing; screw 53 providing a stop for trigger arm 46, and screw 55 54 providing a stop for trigger arm 41. By backing off screw 54 the amount of overlapping engagement between pawl 38 and arm 21 is increased, thereby increasing the pull movement necessary for the trigger to release the sear. By 60 tightening up on this screw the release points 41 and 42 are brought closer together, thus shortening the trigger movement. By this adjustment I have succeeded in getting small trigger release movements without difficulty, such as movements 65 of about five thousandths at the center of the trigger.

By adjusting the setting of stop screw 53, the amount of trigger movement after release may be made very small. This back lash movement is undesirable, and may be substantially entirely eliminated in my structure by proper setting of screw 53. These screws, like plug 52, are adjustable from the base of the housing, and any one of the adjustments may be made without dismantling the gun. This convenience is highly

2,249,231 desirable, especially tn competition matches, where certain conditions such as minimum poundage are specified.

Another screw Βδ is threaded into pawl 38 and is adapted in certain adjustments to abut an in- 5 side wall of the housing for holding the pawl in a selected position while screw 54 holds the trigger in another position. By this special adjustment the “double” pull used in military rifles is obtainable. Figure 1 shows the double pull setting, 10 in which action the trigger is first pulled back a predetermined distance, independent o£ pawl 38, before arm 46 starts moving the pawl.

In the operation of my improved trigger mechanism, the cocking action of bolt 11 draws back 15 the firing pin until lug 18 drops behind the sear lug 34. At this time sear spring 36 lifts the sear arms and allows springs 51 and 49 to reposition the trigger elements, as shown in Figure 3. This resetting of the mechanism therefore occurs auto- 20 matically when the firing pin is cocked. When the triggey is pulled to disengage the release points 41 and 42, the sear again drops down to free the firing pin. In the extended position of the pin its lug 34 is still on top of sear lug 34 25 and serves to hold the sear down, as shown in Figure 2, so that the firing pin lug 34 is free to slid back over and drop behind the sear lug when the firing pin is again retracted.

One special advantage of my mechanism is that 30 it accurately stays in adjustment because of the light pressure exerted on the trigger elements by the sear. In my arrangement of parts a main spring exerting a thrust of say about thirty pounds when cocked is held by an upward force 35 of but about one pound under the sear. Since the sear is supported by the upright pawl 38 the reaction force of even this small load on the pawl is directed entirely against the pawl pin 39, thereby eliminating all transverse forces in the trigger 40 elements due to the main spring. Therefore the adjustments in the trigger elements are made independent of the main spring thrust.

Another feature of my mechanism is that it increases the firing pin speed by reason of offering 45 less resistance to the pin after release. The floating pivot 32—33 of the toggle sear causes the firing pin holding lug 34 to drop away from and in a direction with the firing pin movement. This feature in conjunction with the fact that there is ^δ® little upward pressure exerted by the sear after the pin is released, results in a very fast firing pin speed. This is important because proper ignition of the powder by the primer depends upon it; insufficient denting of a primer by the firing pin ^δδbeing responsible for miss fires and hang fires.

The unit character and ruggedness of the construction are also important; and another feature of the mechanism which promotes structural integrity is that the pivot pins are seated in recess 60 provided in the side plates of the housing, instead of holes bored completely through. This effectively prevents the pins from becoming loose or falling out.

In mounting my unit, the housing is pinned to ⁸⁵the receiver separate from the stock, and then both housing and receiver are lowered down into position on the stock. After the receiver has been secured by studs 7, and the bolt inserted, the ₇₀clamping screw 24 is threaded in from the bottom of the stock and tightened against the receiver to lock the housing. For purposes of adjustment, suitable holes 57 are provided in the trigger guard to receive a screw driver, and a slot 58 is also 75 provided for allowing the trigger to drop down when the housing is lowered.

A modified form of trigger mechanism is shown in Figure 4, in which the toggle sear comprises three arms, instead of two. In this case arms 6i and 62 connected by an elbow pin 63 comprise one toggle joint; and arms 62' and 64 connected by another elbow pin 66 comprise another toggle joint. Arm 61 of the upper toggle carries the firing pin engaging lug 67, and is pivoted on a fixed pivot pin 68. Arms 62 and 64 are arranged upright below the arm 6 ί to support the latter, and arm 64 is pivoted on a fixed pivot pin 69. By this arrangement collapsing of arms 62 and 64 of the lower toggle joint allows collapsing of arms 61 and 62 of the upper toggle joint, thereby releasing the firing pin.

The arms of the lower toggle are held slightly off the vertical by a stop pin 71, so that these arms tend to collapse under the downward pressure of the firing pin. Since these toggle arms are substantially upright however, the retaining force necessary to keep them so is very slight; the major portion of the firing pin thrust being taken by the fixed pivots 68 and 69. A suitable tension spring 72 is provides for urging the sear arms into cocked position after the firing pin has been released.

The trigger in this arrangement has two arms, as in the construction first described, but in this case the sear release element or pawl 73 is positioned above the trigger arms on a pivot pin 74. The rear end of the pawl rests on the trigger arm, and a spring 76 is provided between the trigger and pawl to hold the release point 77 of the latter in engagement with the release point 78 of the sear. When the parts are in cocked position, as shown in Figure 4, the toggle arms 62 and 64 are held upright. When the trigger is pulled however, arms 62 and 64 collapse, allowing arm 61 to drop down and release the firing pin.

Another modification of my trigger mechanism, adapted for a hammer gun, is shown in Figure 5. This is also a three arm combination, except that in the present case one of the arms 81 carries a hammer 82 as the element to be released. A leaf spring 83 presses the hammer forward, and arms 84 and 86 with their elbow pin 87 slightly off center serve to direct the major portion of the thrust against a fixed pivot 88. In this mechanism the parts are recocked by the operator pulling back the hammer.

Throughout the specification and claims the term “cocked element” is used broadly as referring to a firing pin, hammer, or other element to be held in cocked position until released by pulling the trigger.