Gas operated firearm

• US 5,726,377 A
• Filed: 06/19/1996
• Issued: 03/10/1998
• Est. Priority Date: 06/19/1996
• Status: Expired due to Term

• Current Assignee: Colt's Manufacturing IP Holding Company LLC
• Original Assignee: Colt's Manufacturing Company LLC (Colt Defense Holding LLC)
• Inventors: Harris, Michael R., Taylor, James F.
• Primary Examiner(s): Carone, Michael J.
• Assistant Examiner(s): Lattig, Matthew J.
• Application Number:
  US08/670,661
• Time in Patent Office: 629 Days
• Field of Search: 89/177, 89/179, 89/190, 89/191.01, 89/191.02, 89/192, 89/193, 89/198, 42/65, 42/69.01, 42/69.03, 42/97
• US Class Current: 89/191.01
• CPC Class Codes: F41A 19/14 Hammers, i.e. pivotably-mounted striker elements; Hammer mountings
• CPC Class Codes: F41A 3/70 Anti-rebound arrangements, i.e. preventing rebound of the bolt out of the firing position safeties for locking the breech-block or bolt in a safety position F41A17/42
• CPC Class Codes: F41C 23/06 Stocks or firearm frames specially adapted for recoil reduction
• CPC Class Codes: F41C 7/00 Shoulder-fired smallarms, e.g. rifles, carbines, shotguns specially adapted for underwater use F41C9/06

Abstract

A known gas operated firearm has been modified to be of more compact size and reduced weight while retaining the firepower, the features, and most of the components of its predecessor. A bolt assembly reciprocably mounted in a longitudinal cavity of a receiver assembly for movement between recoil and battery positions has a forwardly facing pressure surface and first and second longitudinally extending coaxial bores. The annular flange of a firing pin is slidable in the second bore and the bolt assembly includes a transversely extending retaining pin engageable by the annular flange to define an aftward terminal position of the firing pin. A recoil assembly includes a pair of tungsten weights mounted in the longitudinal cavity for rectilinear movement with the bolt assembly between the recoil and battery positions and includes means to bias the bolt assembly toward the battery position. A trigger mechanism includes a hammer biased for movement toward the firing position from a cocked position whose recessed face squarely impacts the firing pin. A second transversely extending recess in the hammer face provides clearance for the transversely extended retaining pin. Expanding gases from a cartridge whose bullet has passed a gas port proceeds past the gas port, then through a gas passage tube and against the pressure surface of the bolt assembly for driving the bolt assembly toward the recoil position. The tungsten weights are of a magnitude coordinated with the velocity of the recoil assembly so as to reduce rebound in the battery position of assembly during automatic fire.

Claims

1. A gas operated firearm comprising:

a receiver assembly having a longitudinal cavity therein;

a bolt assembly extending between forward and aft ends mounted in the longitudinal cavity for reciprocal movement between recoil and battery positions and having a forwardly facing pressure surface, said bolt assembly having first and second longitudinally extending coaxial bores therein and including an elongated firing pin having a main shaft slidable in the first bore extending between a head and a firing base and an annular flange intermediate said head and said firing base, said annular flange being slidable in the second bore, said bolt assembly including a transversely extending retaining pin engageable by said annular flange to define an aftward terminal position of said firing pin on said bolt assembly;

a recoil assembly mounted in the longitudinal cavity for rectilinear movement with said bolt assembly between the recoil and battery positions, said recoil assembly including means to bias said bolt assembly toward the battery position;

a trigger mechanism including;

a hammer mounted for movement between a cocked position distant from said firing base of said firing pin and a firing position engaged therewith;

means biasing said hammer toward said firing position;

a trigger having a trigger sear thereon engaged with said hammer to hold said hammer in the cocked position, said trigger being selectively movable to disengage said trigger sear from said hammer allowing movement of said hammer toward the firing position under the bias of said biasing means;

a barrel mounted on said receiver assembly at a receiving end defining a firing chamber and extending to a distal end and having a longitudinally extending barrel bore coaxial with the first and second bores in said bolt assembly and having a gas port intermediate said receiving end and a discharge end of the barrel;

a gas passage tube extending between the gas port and said pressure surface for directing expanding powder gases, from a cartridge after a bullet thereof has traveled outwardly through the barrel bore, through the gas port, then through said gas passage tube, then against said pressure surface for driving said bolt assembly toward the recoil position;

characterized in that said hammer including a hammer face having a first recess with a base surafce for squarely impacting said firing base of said firing pin and a second transversely extending recess for reception of said retaining pin when said hammer reaches the firing position.

2. A gas operated firearm as set forth in claim 1 including:

means operable for feeding a fresh cartridge into the firing chamber after a spent cartridge has been ejected therefrom when said bolt assembly is in the battery position.

3. A gas operated firearm as set forth in claim 1:

wherein said recoil assembly includes a buffer mounting an elongated mass segmented into a plurality of coaxial weights, said weights having a lost motion connection with said buffer and with each other for transmitting to said bolt assembly the force resulting from their inertia.

4. A gas operated firearm as set forth in claim 3 including:

wherein said weights are of a magnitude coordinated with the velocity of said recoil assembly so as to reduce rebound in the battery position of said assembly during automatic fire.

5. A gas operated firearm as set forth in claim 3

wherein said buffer includes a bumper having a low coefficient of restitution engageable with the end of the longitudinal cavity in recoil position to minimize the shock of recoil movement.

6. A gas operated firearm as set forth in claim 3

wherein a plurality of washers having a low coefficient of restitution are disposed between each adjacent pair of said weights.

7. A gas operated firearm as set forth in claim 3

wherein said plurality of weights are disposed within a longitudinal cavity provided by said buffer.

8. A gas operated firearm as set forth in claim 7

wherein the longitudinal cavity provided by said buffer is sealed against the entry of contaminants.

9. A gas operated firearm as set forth in claim 3

wherein said buffer includes two weights composed of tungsten.

10. In a firearm having a frame, a barrel connected to the frame, and a firing mechanism connected to the frame, the firing mechanism having a firing pin and a hammer pivotably connected to the frame for striking the firing pin, wherein the improvement comprises:

the hammer having a hammer face with a first recess having a recessed base surface for directly contacting the firing pin when the hammer strikes the firing pin.

11. A firearm as in claim 10 wherein the hammer face has a second recess therein.

12. A firearm as in claim 11 wherein the second recess extends transversely across the hammer face, the second recess receiving a retaining pin on a bolt carrier of the firing mechanism when the hammer strikes the firing pin.