US 3580132 A
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United States Patent 72] Inventor Edwin S. Vartanian Primary Examiner-Benjamin A. Borchelt North Haven, Conn. Assistant ExaminerStephen C. Bentley  Appl. No. 762,593 Attorneys-H. Samuel Kieser, Donald R, Motsko, William W. I 22] Filed Sept. 25, 1968 Jones, Richard S. Strickler, Robert H. Bachman, Donald R. Patented y Motsko and Thomas P. ODay  Assignee Olin Mathieson Chemical Corporation ABSTRACT: A mechanism for reducing the recoil force  BUFFER AND'DELAY MECHANISM FOR A caused by reciprocation of a bolt assembly in a semiautomatic FIREARM tirearm, and for delaying thbe return of the boll; assgmlglly fLom Mms its retire osition to its attery position. si e 0c is 7 C 5 Drawing Figs. mounted fo r reciprocation adjacent to the barrel, and the bolt [$2] 0.8. CI 89/130, assembly is mounted f reciprocation within the receiver A 89/191, 89/198 89/199 pair of slide arms are secured to the bolt assembly and extend  Int. Cl F4ld 5/04, toward the Slide block, normally abutting the m A spring F 41d l1/12 engages the slide block to deceleratc the latter during rear-  new of 89/130 ward reciprocation thereof. The slide block thus decelerates 199 during its rearward stroke while the bolt assembly and slide References Cited arms are thus free to move away from the slide block to strike the rear of the receiver and rebound forwardly therefrom. UNITED STATES PATENTS After rebound, the slide arms and bolt assembly strike the 891,778 6/1908 Mertens 89/ l 99UX rearwardly moving slide block to cause a pause in the recipro- 1,344,991 6/1920 Cunningham 89/191X cation cycle, after which pause the slide block, slide arms, and 1,382,058 6/1921 Bourdelles 89/198X bolt assembly all move forward to their original positions 2,451,624 10/ 1948 Loomis et a1. 89/130 under the influence of the spring.
3,2 22 A5 /7ZY f iefl 1:1 1. '1 1 1 r r' 44 P v H I I I 4 1 41 4 Z4 Z4 20 This invention relates to a mechanism for reducing the recoil force and therefor increasing the life of the gun caused by the reciprocation of the bolt assembly in a semiautomatic firearm as the bolt assembly is moved from its battery position to its retired position and returned. The mechanism also provides for delaying the return movement of the bolt assembly from its retired position to its battery position to permit a greater time period for the operation of the cartridge extractor ejector and the feeding of a new cartridge into a position to be picked up by the bolt assembly and seated in the firing chamber.
The prior art semiautomatic firearms of the type utilizing a reciprocating bolt assembly have exhibited several undesirable traits relating to the reciprocation of the bolt assembly.
When the conventional bolt actuated semiautomatic firearm is fired, the bolt assembly is driven from its battery position to a retired position and return. The-bolt assembly, upon reaching the retired position, strikes the rear; face of the receiver thus delivering a recoil shock to the receiver and shooter; This recoil shock is considerable due to the relatively large mass of the bolt assembly needed to ensure complete reciprocation of the bolt assembly. It is desirable to reduce the quantum of shock delivered to the receiver and shooter without reducing the total mass of the bolt assembly in order to concurrently provide for a more durable mechanism and more comfortable shooting while insuring dependable reciprocation of the bolt assembly.
A second undesirable feature of the prior art bolt actuated semiautomatic firearms relates to the time period during which the bolt assembly is approximately in its retired position. The time period during which the bolt assembly is in its retired position is critical because it is during this period that the fired cartridge casing is ejected from the firing chamber and a fresh cartridge is positioned for feeding into the firing chamber. The bolt assembly must be in its retired position for a predetermined minimum time period in order to insure'that these several operations are completely performed. Should the bolt assembly be returned to its battery position before these operations are completely performed, jamming of the action of the gun will occur. Therefore, in order to insure that the specified operations are completely performed before the bolt assembly is returned to its battery position, it is desirable to delay the bolt assembly in or adjacent to its retired position.
The preferred embodiment of the mechanism of this invention includes a bolt assembly comprising a bolt slide and a bolt reciprocally mounted in the receiver of a fireann. A slide block member is reciprocally mounted for sliding movement beneath and parallel to the barrel of the firearm, the slideblock being acted upon by a gas piston after a cartridge is fired from the gun. A pair of slide arms are connected to the bolt assembly and are spring biased into abutting engagement with the slide block. A return spring is operative to act upon the slide block to bias the latter toward the gas piston. When the bolt assembly is in its battery position, the slide block is disposed adjacent to the gas piston and the slide arms are abutted against the slide block, so that the bolt assembly, the slide block, and the slide arms form an interconnected mechanism. When a cartridge is fired, the gas piston acts upon the slide block to impel the latter rearwardly on the gun. The rearward movement of the slide block forces the latter against the slide arms to move the slide arms and the bolt assembly rearwardly toward the retired position at a first velocity. Thus the initial portion of the reciprocation of the mechanism is accomplished with the slide block, slide arms, and bolt assembly all moving as a unit. Rearward movement of the slide block compresses the slide block spring, which in turn operates to decelerate the slide block. The bolt assembly and slide arms are not, however, decelerated, and continue to move rearwardly at substantially their initial velocity. The resulting difference in respective velocities causes the bolt assembly and slide arms to move away from the slide block, and the slide arms are thus moved out of abutment with the slide block. The bolt assembly and slide arms continue to move rearwardly independently of the slide block until the bolt assembly strikes the rear of the receiver and rebounds forwardly. The forwardly movingbolt assembly and slide arms then strike the rearwardly moving slide block and the bolt assembly, slide arms, and slide block momentarily cease movement in either direction. The slide block spring then acts against the slide block to carry the slide block, the slide arms, and the bolt assembly back to their respective original positions. The mass of the bolt assembly and slide arms on one hand, and the slide block on the other hand are chosen so as to cause a halt in the motion of the components upon impact between them. The resultant halt in movement provides for an extended time period during which the cartridge extraction and ejection, and fresh cartridge feeding are insured of being fully performed. Also the bolt assembly and slide arms are the only components of the system which rebound against the receiver, thus the shock delivered to the receiver and stock, and to the shooter after the gun is fired is substantially reduced.
It is therefore, an object of this invention to provide a bolt actuating mechanism in a semiautomatic firearm wherein the recoil force on the receiver and that experienced by the shooter from reciprocation of the mechanism is substantially reduced.
It is a further object of this invention to provide a bolt actuating mechanism of the character described wherein an extended actuating time period is afforded to insure that the fired cartridge is extracted and ejected, and a fresh cartridge is properly fed into position for chambering.
It is yet another object of this invention to provide a bolt actuating mechanism of the character described wherein the bolt assembly and slide block move as a unit during one stage of the actuation, and the bolt assembly moves independently of the slide block during another stage of the actuation.
It is still a further object of this invention to provide a bolt actuating mechanism of thecharacter described wherein the momentum of the bolt assembly and the opposite momentum of the slide block are operative to stop movement of the mechanism for a predetermined time period during-operating of the mechanism. 1
These and other objects and advantages of this invention will become more readily apparent from the following detailed description and accompanying drawings in which:
FIG. 1 is a sideelevationpartially in section of a portion of a firearm incorporating a preferred embodiment of the bolt actuating mechanism of this invention, the bolt assemblybeing shown in its battery position;
FIG. 2 is a top view of the slide block taken along line 2-2 of FIG. 1, showing the means with which the slide arms are maintained in abutment against the slide block;
FIG. 3 is a side sectional view taken along line 3-3 of FIG. 2;
FIG. 4 is a slide elevation partially in section similar to FIG. 1, but showing the bolt assembly and slide arms having moved relatively away from the slide block during the actuation of the mechanism and while all three elements are movingrearwardly on the gun; and
FIG. 5 is a side elevation partially in section similar to FIG. 4.
Referring now to FIG. 1, a bolt actuated semiautomatic firearm, denoted generally by the numeral 2, is shown. Various parts of the firearm, such as the trigger assembly, hammer assembly, and cartridge magazine have been omitted for purposes of clarity. It' is understood that a conventional trigger assembly, hammer assembly, and cartridge magazine may be used with this invention without departing from the spirit thereof. The firearm 2 includes a receiver 4, a barrel 6 connected thereto, and a stock 8, all of which are of a conventional nature and form no part of this invention. A forearm 10 is mounted on the barrel 6 to house the mechanism of this invention. A bracket 12 being hollowed out to contain'a gas chamber 14. A gas bleed port 16 is drilled through the bracket 12 and the barrel 6 to provide fluid communication between the gas chamber 14 and barrel bore 18 through which port 16 high-pressure gases are bled from the bore 18 into the chamber 14 after a bullet is fired from the gun. A piston 20 is slidably mounted in the chamber 14, the piston 20 being operable to act upon a slide block 22 movably mounted below the barrel 6. The slide block 22 includes a yoke portion 24 and a pair of laterally extending shoulders 26, the latter of which provide abutting surfaces against which the forward ends 28 of a pair of slide arms 30 are disposed. Each of the slide arms 30 includes a keyhole slot 32 in which a laterally extending pin 34 is slidably mounted. The underside of the slide block 22 is hol lowed out at 36 to provide a surface 38 against which the forward end of a return spring 40 is disposed. The rearward end of the return spring 40 is seated against the front wall 42 of the receiver 4. The slide arms 30 extend rearwardly through a pair of slots 44 in the receiver wall 42, and the rearward ends of the slide arms 30 are connected to a conventional bolt assembly 46 having a bolt member 47 reciprocally mounted on a pair of rails 48 (only one of which is shown) in the receiver 4.
Referring now to'FlGS. 2 and 3, details of the means for maintaining the abutting contact between the slide arms 30 and the slide block 22 are shown with greater clarity. A spring member indicated generally by the numeral 50 is disposed in the slide block yoke 24, the spring 50 including a pair of laterally offset coil portions 52 interconnected by a laterally extending bar 54. The coil portions 52 each are integral with an upwardly extending finger portion 56. The bar 54 bears against the rear face 24 of the yoke 24 and the upwardly extending fingers 56 bear against the pin 34 to force the latter against the forward ends of the respective slide arm slots 32. The forward ends 28 of the respective slide arms 30 are thus forced by the spring 50 against the respective laterally extending shoulders 26 on the slide block 22. It will be readily appreciated that the slide arms 30 are thus not connected to the slide block 22, but rather merely abut the slide block 22.The slide arms 30 can be moved away from the slide block shoulders 26 by simply overcoming the force of the spring 50.
Referring to FIG. 5, the mechanism of this invention is shown during the rearward stroke of the bolt actuation after a cartridge is fired from the gun. After the bullet passes the bleed port 18 high-pressure gases are introduced into the gas chamber 14 causing the piston 20 to move toward the rear of the gun and strike the slide block 22. The slide block 22 is thus driven to the rear against the slide arms 30 causing the bolt assembly 46 to move toward its retired position in the receiver 4. Thus the slide block 22, slide arms 30, and bolt assembly 46 move rearwardly as a unit during the initial portion of the rearward stroke of the mechanism. Rearward movement of? the slide block 22 compresses the return spring 40, which in turn tends to slow the rate at which the slide block 22 moves rearwardly. Since the slide arms 30 are not rigidly secured to the slide block shoulders 26, the resistance of the spring 40 is not transferred to the bolt assembly 46 and slide arms 30 except negligibly through the spring 50. Thus, while the slide block 22 is decelerated by the spring 40, the bolt assembly 46 and slide arms 30 continue to move rearwardly at substantially their original velocity. It is thus readily apparent that a point will be reached during the rearward stroke of the mechanism when the bolt assembly 46 and slide arms 30 will move away from the slide block shoulders 26. Such a point is shown in FIG. 4, the slide block shoulders 26 being spaced apart from the forward ends 28 of the slide arms 30.
Referring now to FIG. 5, the mechanism is shown after the bolt assembly 46 has struck the rear wall 58 of the receiver 4 and begun to move forwardly in the direction of the arrow 60 toward its battery position. At the same time the slide block 22 is still moving rearwardly in the direction of the arrow 62. The slide arms 30 are thus moved toward the slide block shoulders 26 to impact the latter. The rearward momentum of the slide block 22 and the forward momentum of the bolt assembly 46 and slide arms 30 are of such magnitude as to cancel each other out at impact. Thus the bolt assembly 46, slide arms 30, and slide block 22 stop movement in either direction momentarily after impact, and since the respective momentums are equal and opposite in direction, no recoil is felt by the shooter v shooter, since the momentums are substantially equal and in when impact occurs. After the pause in relative movement occurs, the return spring 40 acts upon the'slide block 22 to return the slide block 22, bolt assembly 46 and slide arms 30 to their respective positions shown in FIG. 1.
It will be readily appreciated that the bolt actuating mechanism of this invention insures complete actuation of the bolt by providing a releasable interconnection between the slide block, the slide arms, and the bolt assembly. This permits the individual elements to move as a unit initially in the rearward actuating stroke thereby gaining high momentum. Subsequently in the rearward stroke, the individual elements move separately with one of them rebounding from a rearward surface before the other of them reaches the rearwardmost point of its movement. Thus the actuation recoil delivered to the receiver and shooter results from a momentum which is one-half the initial momentum of the mechanism, thus doubling the life of the receiver and is, of course, more comfortable for the shooter. After the actuation recoil occurs, the separated elements are moving in opposite directions with substantially equal momentum. The separated elements then collide with each other with the result that relative motion in the mechanism stops for a predetermined time period, thus extending the overall duration of the actuation time. It is noted that the collision results in substantially no recoil to the opposite directions. The extended period of the actuation time insures complete extraction and ejection of the spent cartridge and feeding of a fresh cartridge into a position for chambering. The mechanism of this invention thus buffers the recoil impact delivered to the firearm receiver and to the shooter and reduces the occurrence of jamming during actuation of the bolt.
Since many changes and variations of the disclosed embodiment of the invention may be made without departing from the inventive concept, it is not intended to limit the invention otherwise than as required by the appended claims.
1. In a firearm having a receiver and a barrel secured thereto, a bolt actuating mechanism comprising:
a. a first body mounted for reciprocating movement adjacent said barrel;
b. a second body' mounted for reciprocating movement within said receiver, said second body including bolt means;
c. elongate means extending between said bodies, said elongate means being secured to one of said bodies and said elongate means being in displaceable abutting contact with the other of said bodies;
d. gas operated means connected to said barrel, said gas operated means being operable to impel said bodies and said elongate means through an actuation cycle having an initial rearward stroke and a subsequent forward stroke;
e. spring means having one of its ends contacting said first body and having the other of its ends contacting a nonreciprocating portion of said firearm, said spring means being operative to decelerate said first body during said rearward stroke to thus move said elongate means out of abutting contact with said other body; and
f. said second body being operative to sequentially strike said receiver and rebound into its forward stroke during the decelerated rearward stroke of said first body to cause said other body to strike said elongate means so as to stop relative movement of said bodies and create apause in said actuation cycle, and to prevent said first body from contributing substantially to the force of impact imparted to said receiver by said bolt actuating mechanism.
2. The bolt actuating mechanism of claim 1, further comprising second spring means operative to bias said elongate means toward said other body.
3. In a firearm having a receiver and a barrel secured to said receiver, a bolt actuating mechanism comprising:
a. first means mounted for reciprocating movement within said receiver, said first means including a bolt assembly;
b. second means mountedfor reciprocating movement adjacent said barrel, said second means abutting said first means; I
0. gas operated means secured to said barrel and operative to impel said first and second means through an actuation cycle having a rearward stroke and a forward stroke;
d. spring means having one end contacting said secondmeans and having another end contacting a nonreciprocating portion of said firearm to bias said second means toward said gas operated means, said spring means being operative to decelerate said second means during the rearward stroke of said actuation cycle to move said second means out of abutting contact with said first means; and
e. said first means being operative to strike said receiver at the end of its-rearward stroke and rebound into said forward stroke, and said first means subsequently being operative to strike said second means to prevent the latter from contributing to the impact imparted to said receiver and to create a pause in said actuation cycle.
4. The bolt actuating mechanism of claim 3 further comprising spring means operative to bias said first means toward said second means. V
5. In a firearm having a receiver and a barrel secure to the receiver, a bolt actuating mechanism comprising:
a. a slide block mounted for reciprocating movement beneath said barrel;
b. a bolt assembly mounted for reciprocating within said receiver;
' c. at least one slide arm means connected to said bolt assembly and extending toward said slide block for abutting contact therewith;
d. gas operated means secured to said barrel forward of said slide block, said gas operated means being operable to impel said slide block, said bolt assembly, and said slide arm means on an actuation cycle having a rearward stroke and a forward stroke;
e. spring means engaging said slide block and a nonreciprocating portion of said firearm to decelerate said slide block during its rearward stroke to move said slide block out of abutting contact with said slide arm means; and
movement f. said bolt assembly being operative to strike said receiver to terminate the rearward stroke of said bolt assembly and to rebound the latter into its forward stroke, and said slide arm means then being operative-to strike said slide block to prevent the latter from contributing to the impact delivered to said receiver and to momentarily stop all relative movement of said mechanism to create a pause in the actuation cycle.
6. The bolt actuating mechanism of claim 5, further comprising spring means operative to bias said slide arm means toward said slide block.
7. In a semiautomatic firearm having a receiver and a barrel secured to the receiver, a bolt actuating mechanism comprismg:
a. slide block means mounted for reciprocating movement beneath said barrel, said slide block means including a yoke and at least one laterally extending shoulder means;
b. a bolt assembly mounted for reciprocating movement within said receiver;
c. at least one slide arm means secured to said bolt assembly and extending toward said slide block means for abutting contact with said shoulder means;
d. laterally extending pin means traversing said yoke and connected to said slide arm means;
e. gas operated means secured to said barrel forward of said slide block means, said gas operated means being operable to impel said slide block means, said bolt assembly, and said slide arm means on an actuation cycle having rearward stroke; first spring means engaging said slide block to decelerate the latter during its rearward stroke thereby movi rg said shoulder means out of abutting contact with sai slide arm means;
g. second spring means engaging said pin means to bias said slide arm means toward said shoulder means; and h. said bolt assembly being operative to strike said receiver to terminate the rearward stroke of said bolt assembly and to rebound the latter into its forward stroke; and slide