US3236154A - Mechanism for reducing the rate of fire in automatic firing arms - Google Patents

Mechanism for reducing the rate of fire in automatic firing arms Download PDF

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Publication number
US3236154A
US3236154A US360297A US36029764A US3236154A US 3236154 A US3236154 A US 3236154A US 360297 A US360297 A US 360297A US 36029764 A US36029764 A US 36029764A US 3236154 A US3236154 A US 3236154A
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United States
Prior art keywords
hammer
sear
slide
lock
spring
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Expired - Lifetime
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US360297A
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English (en)
Inventor
Iwashita Kenzo
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Howa Kogyo KK
Howa Machinery Ltd
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Howa Machinery Ltd
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Publication date
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F41—WEAPONS
    • F41A—FUNCTIONAL FEATURES OR DETAILS COMMON TO BOTH SMALLARMS AND ORDNANCE, e.g. CANNONS; MOUNTINGS FOR SMALLARMS OR ORDNANCE
    • F41A19/00—Firing or trigger mechanisms; Cocking mechanisms
    • F41A19/03—Shot-velocity control

Definitions

  • the present invention relates to mechanism for reducing the rate of fire in automatic rifles and more particularly to an improved arrangement of trigger, sear and hammer components, as well as additional mechanism for adjustably selecting one of fully automatic firing, short or single firing and no firing operations.
  • the mechanism should be so constructed that the motions of a reciprocating member, such as a slide, and a firing mechanism, such as a hammer, etc., may be well balanced and smooth and that these components can reciprocate in as straight a line as possible.
  • a reciprocating member such as a slide
  • a firing mechanism such as a hammer, etc.
  • a further object of this invention is to provide a novel mechanism which is quite simple, but can operate accurately without any trouble, reduce the rate of fire, and eliminate any moment that tends to disturb the maintenance of the aim.
  • a mechanism for reducing the rate of fire in automatic rifles of the type comprising a firing pin, a hammer, a chamber for the hammer, a hammer spring associated therewith for actuating the hammer to strike the firing pin, a slide, a recoil spring for said slide, said slide together with said hammer being guided in the hammer chamber for advance movement in a straight line towards the firing pin, means for retracting the hammer together with the 'slide 3,236,154 Patented Feb.
  • a receiver in which said hammer, slide, firing pin and recoil spring are arranged, a receiver tail containing the hammer spring, a hammer stop and being capable of having inserted therethrough substantially all of said hammer when the same is retracted, a sear adapted to lock the hammer in the retracted position, a trigger for triggering the hammer at said retracted position, a sear lock mounted for pivotal movement, a front projection on the sear lock adapted to be displaced downwardly at the termination of the return of said slide, a rear projection on said sear lock adapted to displace upwardly the forward end of said sear when the front projection is displaced downwardly thereby releasing the hammer, a scar lock spring urging said sear lock to normally displace said front projection upwardly, a connector pivoted to the sear lock at the pivotal mounting for the sear lock for adapting the fire arm to any state of continuous shot, single shot and safety, means defining a trigger
  • FIG. 1 shows an operation diagram of a mechanism embodying this invention
  • FIG. 2 shows an operation diagram of a mechanism employed in the conventional weapon for reducing the rate of firing thereof
  • FIG. 3 is a view in longitudinal section, partly broken away, illustrating the arrangement of all members ofa mechanism constructed according to this invention
  • FIGS. 4 and 5 are sectional views respectively showing relative positions of the respective members for automatic firing operations with FIG. 4 showing the state of readiness before the trigger is actuated by the shooter, and FIG. 5 the state wherein the trigger has been actuated;
  • FIGS. 6 and 7 are sectional views respectively showing the relative positions of the respective members for single shot firing operation with FIG. 6 showing the state of readiness, and FIG. 7 the state wherein the trigger has been actuated; i
  • FIG. 8 is a similar view illustrating the safety condition of the mechanism of FIG. 3;
  • FIG. 9 is an exploded view of a trigger and its asso ciated members of the mechanism of FIG. 3;
  • FIG. is a side view partly in elevation and partly in cross section illustrating the mutual relation of a trigger and a sear when they are engaged in the mechanism of FIG. 3.
  • a slide is pushed backwardly by gas pressure or other motive force after one shot has been fired. Near the end of the backward stroke, the slide strikes the head of an actuator to cause it to retract while compressing a spring positioned behind the actuator until it stops at a balance point. Thereafter, the spring acts to push the actuator in the forward direction.
  • the slide begins its forward movement from the stroke end thereof under the action of a recoil spring, but it is locked by a slide lock at the initial stage of its forward movement.
  • the actuator advances to release the slide lock at the end of its forward stroke the slide again begins to advance forwardly to charge the succeeding cartridge into the firing chamber just before the end of its stroke, thus completing the breech lock.
  • a hammer is generally pivotally mounted in a trigger housing so that the hammer will be pushed back at its head by the slide at the initial stage of the retracting stroke thereof to be rotated around a pivot pin while moving backwardly until it is locked by a sear.
  • the slide advances, the hammer is released from the sear immediately after completion of the breech locking operation and then advances over a relatively short distance while rotating under the action of a hammer spring until it strikes the rear end of a firing pin to effect the next firing.
  • a further outstanding feature of the mechanism of this invention is that the motion of the hammer is rectilinear. This means that a mechanism incorporating the first fea ture involves the second feature also. It will be clear that the construction in which the hammer is adapted to strike a firing pin during its motion along a straight line can greatly minimize any moment that may cause disturbance of the aim of the weapon when compared with the conventional construction wherein the hammer is rotated to hit the firing pin.
  • Another outstanding feature of the mechanism constructed according to the principle of this invention is that the respective members thereof are completely free from any disarrangement even when the rifie is subjected to an abnormal shock.
  • conventional mechanism however, there are frequent cases in which the safety lock is caused by such shock to become ineffective even when it is originally set to operate.
  • this invention such a defect is obviated by designing the sear so as to minimize the tendency to affect the locking function thereof or to rotate it about the axis of its pivot pin even when an impact from the outside is applied to the weapon in any direction and by interlocking the hammer and the sear in a hook fashion.
  • the mechanism is constructed so that actuation of the trigger by finger will cause firing of the first cartridge, and immediately thereafter the slide will retract and then advance to charge the next cartridge into the firing chamber. Even if the shooter continues to hold the trigger, subsequent firing is prevented, and when the shooter releases the trigger it is permitted to return to its initial position, so that only when the shooter actuates the trigger again, the next shot is fired.
  • FIG. 3 which illustrates one embodiment of this invention, there is shown a reciprocating mass 1 including a slide and a bolt (not shown) adapted to charge and remove a cartridge, not shown, in the manner well known in the art.
  • a firing pin 2 is arranged in a conventional manner.
  • a trigger 3 is pivotally mounted by a pivot pin 5, said trigger being biased in the counterclockwise direction, as viewed in the drawing, by a trigger spring 6 acting thereupon through a trigger pusher 7.
  • a scar 8 is mounted within the housing 4 by means of an elongated slot 8a and a pin 9 passing therethrough.
  • the sear 8 is biased toward the left upper side by a scar spring 10 disposed below the pin 9, so that the rear extension 8f of the sear 8 will be rotated in the clockwise direction until it is engaged by the lower surface 11 of the receiver R.
  • a hammer 12 is constructed so that it will retract together with the slide 1 but will advance independently of the forward movement of the slide.
  • a hammer spring stop 14 provided with a shaft 14a about which the spring 13 is wound. The stop and shaft are inserted in the receiver tail R so as to slide therethrough.
  • a hook shaped projection 12a is formed on the fore end of the hammer 12.
  • the slot 8a is so machined as to position the pin 9 substantially at the center of gravity of the sear 8 when -it is displaced to the right under the bias of the hammer spring 13.
  • the sear 8 is positively prevented from rotating about the pin 9 by an impact imparted thereto by unexpected strong outside shock. Even the slightest tendency for such a rotation can be precluded by providing slightly inclined engaging surfaces between the projection 12a on the hammer 12 and the projection Sr: of the sear as best shown in FIG. 10, These inclined engaging surfaces can positively prevent not only unexpected firing in the case of the trigger being slightly pulled inadvertently, but also accidental firing caused by impact due to dropping of the rifle and other causes.
  • the stroke of -the hammer 12 is very long and is rectilinear, which is an important factor in reducing the firing rate, because a longer stroke requires a longer time for traverse.
  • the effective hammering mass is the sumof the mass of the hammer 12, that of the hammer spring stop 14 including that of shaft 14a since the hammer stop and shaft advance as a unitary component in the firing operation.
  • this invention provides a novel mechanism of high utility without the possibility of any trouble, which mechanism is also capable of reducing the rate of fire and greatly improving the firing accuracy.
  • a mechanism for reducing the rate of fire in automatic fire arms, particularly automatic rifles of the type comprising a firing pin, a hammer, a chamber for the hammer, a hammer spring associated therewith for actuating the hammer to strike the firing pin, a slide, a recoil spring for said slide, said slide together with said hammer being guided in the hammer chamber for advance movement in a straight line towards the firing pin, means for retracting the hammer together with the slide until a dead point is reached, a receiver in which said hammer, slide, firing pin and recoil spring are arranged, a receiver tail containing the hammer spring, a hammer stop and being capable of having inserted therethrough substantially all of said hammer when the same is retracted, a sear adapted to lock the hammer in the retracted position, a trigger for triggering the hammer at said retracted position, a sear lock mounted for pivotal movement, a front projecion on the sear lock adapted
  • the assemblage including the sear and trigger combined with the sear lock includes a scar lock pin constituting the pivotal mounting for the sear lock, said connector having at one end thereof an open slot, a fixed pin received in said open slot, said sear lock spring being defined by a leaf spring, and an eccentric pin carried by said connector for being positioned at any desired angle whereby adjusting of such latter pin adapts the fire arm for continuous firing, single shot firing and safety.
  • a sear lock 19 having a projection 19a disposed to be pushed down by the returning motion of the slide 1, is connected, by a pin 20, to a connector 16 which in turn is supported in the trigger housing 4 by a pivot pin 18, a projection 19b on the end opposite to said projection 19a being normally urged in the counterclockwise direction by a leaf spring 21.
  • the rotation of the sear lock 19 in the clockwise direction induces the rotation of the sear 8 in the counter-clockwise direction, which, of course, is induced by contact between the projection 19b against the projection 8d.
  • these pnojections are out of phase, or when the sear 8 is displaced to the right, as viewed in the drawing, along the elongated opening 8a such a transmission of motion does not occur.
  • the sear 8 is formed to have a pointed edge 81) and a lower surface 80, and the trigger 3 is provided with an inclined surface 3c, the purpose of which will be described later.
  • the hammer 12 is shown in its position when it is locked by the sear 8. This state of locking is quite stable, owing to a lock fashioned joint between the rear projection 8c of the sear 8 and the projection 12a on the hammer 12, which cannot be disengaged by any abnormal shock imparted from the outside.
  • the arm 3a of the trigger 3 engages the lower surface 80 of the sear 8 to push it upwardly, thereby to rotate the sear 8 in the counter-clockwise direction around the pivot pin 9 to release the hammer 12.
  • the hammer 12 is advanced rapidly under the bias of the hammer spring 13 to strike the firing pin 2, thereby firing cartridge, not shown, at the end of its forward stroke.
  • the pivot pin 9 of the sear 8 is at the righthand end of the slot 85!, but, upon release of the trigger 3, the edge 8b disengages from the inclined face 3c, whereby the hammer 12 pushes the sear 8 to the right until the pin 9 reaches the lefthand end of the slot 8a, thus bringing the projections 8d and 19b into an out-of-phase relation.
  • the projection 1% does not raise the projection 8d, thus assuring continuous locking of the hammer to prevent furthere firing operation.
  • a relatively large space is provided for the strokes of the hammer 12 which is constructed to reciprocate linearly along the longitudinal axis of the firearm. This contributes to providing a recoiling effect with almost no effect with respect to the center of gravity of the firearm, thus effectively improving the firing accuracy.
  • the projection 19a of the sear lock 19 is kept in a position such that the projection is not affected in any way by any movement of the slide 1, as can be clearly understood by comparing FIGS. 4 and 6. Means for providing this feature will be described hereinbelow by referring to FIG. 9.
  • this means comprises a connector 16 having an open slot 16a at its one end for receiving a transversal pin 17 secured to the trigger housing 4.
  • the opposite end of the connector 16 is held by an eccentric pin 18 forming an extension of a pin 18a journaled in the side walls of the trigger housing 4.
  • the connector 16 can be positioned at any desired angle.
  • the eccentric pin 18 When the eccentric pin 18 is positioned in the extreme righthand position (FIGS. 4 and 5), the mechanism is set for the continuous automatic firing operation, whereas, when it is positioned in the extreme lefthand position (FIG. 8), the vertical end face 16b of the connector 16 abuts the front vertical surface of the trigger 3, thus causing it to become inoperative. In other words, such an abutment serves as a safety device.
  • a suitable buffer 15 is provided at the upper left side of the trigger housing 4 and as has been pointed out hereinabove, it will be understood that the slide 1 is returned to its righthand position by a conventional recoil spring, not shown.
  • Another feature of the mechanism embodying this invention is the capability of holding the sear 8 in a state for automatic firing operation without relying upon any additional mechanism, this feature being provided by suitably shaping the trigger 3 and the sear 8 so as to come into direct contact. More particularly, the sear 8 is biased to rotate clockwisely around the pin 9 by a spring 10 while the hammer spring 13 urges the sear 8 to the right. Of course, the force of the hammer spring 13 is much greater than that of the spring 10. This means that unless a suitable means is used to prevent the sear from moving to the right, it is impossible to provide automatic firing operation.
  • the trigger 3 it is necessary for designing the trigger 3 so that the sear is positively held against the strong hammer spring 13, the shooter is permitted to hold the trigger in its actuated position, and when released by the shooter, the trigger is positively returned to its released position under the action of the trigger spring 6 transmitted thereto through the trigger pusher 7.
  • this invention contemplates selecting the angle a (FIG. 10) between a line passing through the point of contact between the hook 8e on the sear 8 and the projection 12a of the hammer 12, and through the point of contact between the pointed edge 8b 9 10 of the trigger the sear is kept in continuous firing position 1,573,655 2/1926 Sutter 89130 With the trigger returning to idle position upon the re- 2,909,100 10/1959 yy 89-140 162156 of the trigger.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Portable Nailing Machines And Staplers (AREA)
  • Percussive Tools And Related Accessories (AREA)
US360297A 1963-06-28 1964-04-16 Mechanism for reducing the rate of fire in automatic firing arms Expired - Lifetime US3236154A (en)

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BE (1) BE647702A (de)
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DE (1) DE1428774C3 (de)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3960053A (en) * 1974-09-20 1976-06-01 Maremont Corporation Automatic firearm having anti-bounce sear
US4023465A (en) * 1975-06-27 1977-05-17 Inskip Thomas C Firearm
US4469006A (en) * 1981-05-12 1984-09-04 Sites S.P.A. Automatic fire-arm
US6634129B1 (en) 2000-08-22 2003-10-21 Richard N. Freeman, Jr. Modified bolt assembly and firing mechanism for an MG 34 Mauser rifle
US20130319389A1 (en) * 2010-12-28 2013-12-05 Chao-Hsiung Cho Air gun firing operating system
US20150308784A1 (en) * 2014-03-06 2015-10-29 Chao-Hsiung Cho Air gun firing control device
US20190107353A1 (en) * 2017-10-10 2019-04-11 Sig Sauer, Inc. Handgun sear with multiple engagement surfaces

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5485776A (en) * 1989-12-16 1996-01-23 Bushman Limited Mechanism for controlling the firing rate of an automatic weapon
GB8928452D0 (en) * 1989-12-16 1990-02-21 Bushman Ltd Mechanism for controlling the firing rate of an automatic weapon
DE4125148A1 (de) * 1991-07-30 1993-02-04 Gerold Domhan Abzugseinrichtung fuer schusswaffen
RU2447388C1 (ru) * 2010-11-18 2012-04-10 Государственное унитарное предприятие "Конструкторское бюро приборостроения" Автоматическое стрелковое оружие

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1561756A (en) * 1924-10-03 1925-11-17 Vickers Ltd Trigger mechanism of machine guns and automatic small arms
US1573655A (en) * 1925-02-20 1926-02-16 Anciens Ets Hotchkiss & Cie Firing regulator for automatic firearms
GB604348A (en) * 1943-01-27 1948-07-02 Eugene Gustavus Reising Improvements in automatic firearms
US2909100A (en) * 1956-12-14 1959-10-20 Kennerley-Tayler Horace Trigger mechanism for firearms

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1561756A (en) * 1924-10-03 1925-11-17 Vickers Ltd Trigger mechanism of machine guns and automatic small arms
US1573655A (en) * 1925-02-20 1926-02-16 Anciens Ets Hotchkiss & Cie Firing regulator for automatic firearms
GB604348A (en) * 1943-01-27 1948-07-02 Eugene Gustavus Reising Improvements in automatic firearms
US2909100A (en) * 1956-12-14 1959-10-20 Kennerley-Tayler Horace Trigger mechanism for firearms

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3960053A (en) * 1974-09-20 1976-06-01 Maremont Corporation Automatic firearm having anti-bounce sear
US4023465A (en) * 1975-06-27 1977-05-17 Inskip Thomas C Firearm
US4469006A (en) * 1981-05-12 1984-09-04 Sites S.P.A. Automatic fire-arm
US6634129B1 (en) 2000-08-22 2003-10-21 Richard N. Freeman, Jr. Modified bolt assembly and firing mechanism for an MG 34 Mauser rifle
US20130319389A1 (en) * 2010-12-28 2013-12-05 Chao-Hsiung Cho Air gun firing operating system
US8833353B2 (en) * 2010-12-28 2014-09-16 Chao-Hsiung Cho Air gun firing operating system
US20150308784A1 (en) * 2014-03-06 2015-10-29 Chao-Hsiung Cho Air gun firing control device
US9372047B2 (en) * 2014-03-06 2016-06-21 Chao-Hsiung Cho Air gun firing control device
US20190107353A1 (en) * 2017-10-10 2019-04-11 Sig Sauer, Inc. Handgun sear with multiple engagement surfaces
US10684087B2 (en) * 2017-10-10 2020-06-16 Sig Sauer, Inc. Handgun sear with multiple engagement surfaces

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Publication number Publication date
DE1428774B2 (de) 1974-07-11
CH414400A (fr) 1966-05-31
BE647702A (de) 1964-08-31
DE1428774A1 (de) 1970-01-08
DE1428774C3 (de) 1975-03-06

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