US3370374A

US3370374A - Firing mechanism with means for adjusting trigger-sear overlap

Info

Publication number: US3370374A
Application number: US522498A
Authority: US
Inventors: Larsson Sven Gunnar Olof
Original assignee: Husqvarna Vapenfabriks AB
Current assignee: Husqvarna Vapenfabriks AB
Priority date: 1965-01-27
Filing date: 1966-01-24
Publication date: 1968-02-27
Anticipated expiration: 1985-02-27
Also published as: GB1092166A; BE675675A; DE1935407U

Description

Feb. 27, 1968 s. G. o. LARSSON 3,370,374

FIRING MECHANISM WITH MEANS FOR ADJUSTING TRIGGER-SEAR OVERLAP Filed Jan. 24, 1966 Patented Feb. 27, 1968 ice 3,370,374 FIRING MECHANISM WITH MEANS FOR ADJUSTING TRIGGER-SEAR OVERLAP Sven Gunnar Olof Larsson, Huskvarna, Sweden, assignor to Husqvarna Vapenfahriks Aktiebolag, Huskvarna, Sweden Filed Jan. 24, 1966, Ser. No. 522,498 Claims priority, application Sweden, Jan. 27, 1965, 1,039/65 Claims. (Cl. 42-69) ABSTRACT OF THE DHSCLOSURE A firearm in which a breech bolt is axially displaceable in and withdrawable from a receiver with such breech bolt having a striker and striker spring. A sear mounted on the receiver is provided with a lug for releasably holding the striker in a cocked position and the sear is provided with a shoulder. A spring pressed trigger mounted on the receiver and having a cocking shoulder for releasably holding the sear in its operative position by the engagement of and the overlapping of the sear shoulder. The cocking shoulder on the trigger is retractable from the sear upon the pulling or squeezing of the trigger. A turnable adjusting means is operably related to the sear and the trigger for adjusting the amount of the overlap and such adjusting means is arranged so as to be accessible from the upper side of the receiver upon the removal of the breech bolt. The adjusting means is capable of reduc ing the overlap only to a predetermined safety limit.

This invention relates to a firing mechanism for sliding bolt-action firearms, and more particularly to hunting and target rifles.

In such rifles, the trigger pull required for firing should be adjustable according to the individual requirements of the shooter and to different shooting circumstances. Such adjustments can usually be made to some extent by eX- change or adjustment of parts of the firing mechanism after the rifle has been disassembled which, however, is troublesome and time-wasting. Furthermore, when assembling the rifle, particularly when screwing the bolt receiver to the stock, an elastic deformation may occur which may require for example, an after-adjustment with file and emery cloth of an exteriorly accessible cocking lug on the sear. Moreover, in rifles in which the trigger moves such a scar lug out of cocking engagement with the striker of the breech bolt, the length of the trigger pull must be relatively long for reasons of safety, considering the relatively large vertical play of the striker. In the known rifles provided with externably accessable turnable means for adjusting the amount of overlap of the cocking shoulders on the sear and trigger, it is diflicult to reset such means in positions previously tested and the overlap can be reduced to nil.

It is an object of the invention to eliminate the above drawbacks, and with such and objects in view, as will hereinafter appear, the invention comprises the novel combinations and arrangements of parts hereinafter set forth and illustrated in the accompanying drawing, in which the sole figure shows a vertical longitudinal section through the pertinent parts of a bolt-action embodying the invention.

The bolt-action shown in cocked position comprises a receiver 1 screwed to a rifle stock 2 and a bottom plate 3 by means of a rear screw 4 and a forward screw (not illustrated). A breech bolt 5 is rectilinearly movable in the receiver and withdrawable thereafter rearwardly, and a sear 8 is pivotally mounted on the receiver by means of a pin 6. The sear is provided with a spring 7, a shoulder 9 and an adjusting screw 10. A trigger 13 is pivotally mounted on the receiver by means of a pin 11 and is provided with a cocking shoulder 14 and a rear arm 15. The breech bolt 5 comprises a forward part 17 having a handle 16 and is turnable in its forward position. A striker in the shape of a firing pin 19 is movable longitudinally, is actuated by a spring 18 and secured to a nut 20 having an obliquely downwardly directed contact surface 21 for an opposite surface 22 on a sear lug 3S situated in an aperture in the tail portion of the receiver. The adjusting screw It) has a slotted head 23 countersunk into the sear 8, an edged portion 2 4 provided, for instance, with two opposite chamfers or depressions, and engaged by a preferably ball-shaped, plunger 25 slidably mounted in the sear 8 and actuated by a spring 26, and a lower, conical terminal 27 engaging a planar surface 28 on the trigger 13 said surface being approximately perpendicula to the retracting direction of shoulder 14 and deviating considerably from the longitudinal direction of screw 10. The trigger spring 12 is confined between the arm 15 and a flanged nut 30 on an adjusting screw 31 having a slotted head 32 in a hole in receiver 1 and a flange 33 in contact with the underside of the receiver under the pressure of spring 12, the nut 39 being kept from turning 'by the sides of a recess 29 in the receiver. The terminal of screw 31 forms an abutment for a set screw 34 in arm 15.

The firing pin is held in the cocked position shown by the sear 8, which by the inclination of the

surfaces

21, 22, is influenced by an obliquely downwardly directed component of the pressure of the striker spring 18, but is held in operative position by the cocking engagement of the shoulders 9, 14. When the trigger is swung backwards manually, the cocking shoulder 14 is retracted and the firing pin thrown forward, the scar being depressed by the surface 21 against the action of spring 7 which keeps the sear lug 35 in contact with the underside of nut 20 in the forward position of the latter. When the trigger is released, spring 12 brings cocking shoulder 14 into contact with a surface 36 on the sear. When the breech bolt together with its surface 21 is thereupon retracted the rear sear part is swung upwardly by spring 7, and spring 12 causes cocking shoulder 14 to fall in front of shoulder 9. By subsequently advancing the breech bolt the cocked position shown is restored. The rifle may in known manner be constructed as a repeating rifle so that reloading after firing is done by turning up, retracting, advancing and turning down the handle 16.

The rearward motion of the trigger after firing is limited by the set screws 31, 34 hitting one another. The length of this motion is adjustable by means of the set screw 34 before mounting the rifle action in the stock and need not be altered thereafter. The weight and length of the trigger pull depends on the confinement length A of spring 12 and the amount of overlap B of shoulders 9, 14, respectively. After removal of breech bolt 5 in a known manner, A and B can easily be adjusted by means of screws 31 and 10, respectively, with their

heads

23 and 32 being uncovered by such removal. Screw head 23 should be arranged to reach the bottom of its hole in the sear when screw terminal 27 has been screwed out so far that B has become reduced to a certain safety minimum. By arranging the cocking engagement between the trigger and sear, and not as usual between the scar and the striker part 21, the overlap becomes independent of the lateral play of said striker part so that said minimum can be made very small, say 0.2 mm, Plunger 25 exerts a resistance against an adjustment of screw 10 and which resistance varies with the angular position of said screw whereby one feels and can count the number of turns or parts thereof through which the screw is being turned, thereby simplifying resetting the screw is positions previously tested.

In the embodiment shown, the trigger shoulder 1 is retractable rearwardly, and sear 8 is mounted to swing clockwise upon firing. The invention can be applied also to bolt-actions wherein the trigger is pivoted below its shoulder and the latter is retractable forwardly, with the sear being mounted to swing counter-clockwise. Instead of an adjusting screw or threaded setting rod 10, one can also use asetting rod which is only rotatable in the scar and which at its lower end carries a setting member in the shape of an eccentric engaging the trigger in the cocked, operative position of the sear. Also other modifications are possible within the scope of the claims which follow:

This invention is not to be confined to any strict conformity to the showings in the drawings but changes or modifications may be made therein so long as such changes or modifications mark no material departure from the spirit and scope of the appended claims.

I claim:

1. A bolt-action firearm comprising in combination: a receiver, a breech bolt axially displaccable in said receiver, and withdrawable therefrom, said bolt including a striker and a striker spring, a sear mounted on said receiver and having a lug for releasably holding said striker in a cocked position, a shoulder on said sear, a spring-pressed trigger mounted on said receiver and having a cocking shoulder releasably holding said sear in its operative position by engaging and overlapping said sear shoulder and retractable therefrom by pulling said trigger, turnable adjusting means operably related to said sear and said trigger for adjusting the amount of said overlap, said adjusting means being arranged to be accessible from the upper side of said receiver upon removal of said breech bolt and said adjusting means being capable of reducing said overlap only to a predetermined safety limit.

2. A bolt-action firearm comprising in combination: a receiver, a breech bolt axially displaceable in said receiver and Withdrawable therefrom, said bolt including a striker and a striker spring, a sear mounted on said receiver and having a lug for releasably holding said striker in a cocked position, a shoulder on said sear, a springpressed trigger mounted on said receiver and having a cooking shoulder releasably holding said sear in its operative position by engaging and overlapping said sear shoulder and retractable therefrom by pulling said trigger, and two trigger pull adjusting rods turnably mounted in different parts of said bolt-action and each having a slotted end accessible from the outside of said receiver upon removal of said breech bolt, one at least of said rods having fixed thereto a flange wider than its slotted end and permanently engaging the part mounting said one rod so as to prevent removal thereof in the direction of its slotted end.

3. A bolt-action firearm comprising in combination: a receiver, a breech bolt axially displaceable in said receiver and withdrawable therefrom, said breech bolt including a striker and a striker spring, a sear mounted on said receiver, a lug on the sear for releasably holding said striker in a cocked position, a shoulder on said sear, a springpressed trigger mounted on said receiver, a cooking shoulder on said trigger releasably holding said sear in its operative position by engaging and overlapping said sear shoulder and being retractable therefrom by pulling said trigger, and two trigger pull adjusting rods turnably mounted in different portions of said bolt-action and each having a slotted end accessible from the upper side of said receiver upon removal of said breech bolt, said rods and said portions mounting same having interengaging means for arresting said rods in positions out of the path of said breech bolt.

4. A bolt-action firearm comprising in combination: a receiver, a breach bolt axially displaceable in said receiver and withdrawable therefrom, said bolt including a striker and a striker spring, a sear mounted on said receiver and having a lug for releasably holding said striker in a cocked position, a shoulder on said sear, a spring-pressed trigger mounted on said receiver, said trigger having a cocking shoulder releasably holding said sear in operative position by engaging and overlapping said sear shoulder and being retractable therefrom by pulling said trigger, and an adjusting rod mounted in said sear for adjusting the amount of said overlap, said adjusting rod being arranged to be accessible from the upper side of said receiver upon the removal of said breech bolt and engaging said trigger in a cocked position of said striker, and a spring-pressed member mounted in said scar and engaging a non-circular portion provided on said rod.

5. A bolt-action firearm comprising in combination: a receiver, a breech bolt axially displaceable in and Withdrawable from said receiver, said breech bolt including a striker and a striker spring, a single sear mounted on said receiver and having a lug for releasably holding said striker in a cocked position, a shoulder on said sear at one extremity thereof, a spring-pressed trigger mounted on said receiver and having opposite said sear extremity a cocking shoulder releasably holding said sear in an operative position by engaging and overlapping said sear shoulder and being retractable therefrom by pulling said trigger, and a substantially vertical rod rotatably mounted in said sear for adjusting the amount of said overlap by contacting a planar surface on said trigger, the upper end of said rod being countersunk in said sear lug and accessable from the upper side of said receiver upon rem-oval of said breech bolt, the retraction direction of the trigger considerably deviating from the longitudinal direction of said rod.

References Cited UNITED STATES PATENTS 1,239,124 9/1917 Nelson.

1,741,281 12/1929 Burton 4269 2,069,887 2/1937 Laudensack 4269 2,249,231 7/1941 Smith 4269 2,274,195 2/1942 Garrison 4269 2,584,299 2/1952 Sefried 42-69 BENJAMIN A. BORCHELT, Primary Examiner.