US-12624910-B1 - Reduced weapon system blowback

Abstract

A reloading firearm featuring a mechanism to reduce the blowback of toxic propellant gasses towards the warfighter. The reloading assembly acts in plural segments to increase the firing chamber-closed dwell time, while limiting adverse impact to the overall nominal rate of fire. Greater dwell time corresponds with reduced exposure of the warfighter to propellant gasses. Moreover, increasing the dwell time without otherwise altering the firing cycle has the additional effect of delaying the breech opening after the cartridge is fired. This delay in breech opening permits gas pressure at the muzzle, which may be elevated and/or constrained by flash and/or sound suppression, to dissipate before the breech is opened. Accordingly, when the breech opens later in the firing cycle, there is a reduced pressure gradient across the combination of barrel and firing chamber, which reduces a driving force of propellant gasses towards the warfighter via the open breech.

Inventors

• Adam L. Foltz
• Francis J. Battersby
• Michael W. Brown

Assignees

• U.S. GOVERNMENT AS REPRESENTED BY THE SECRETARY OF THE ARMY

Dates

Publication Date

20260512

Application Date

20241213

Claims (18)

1. 1 . An operating rod apparatus for a reloading firearm, the operating rod apparatus being translatable from a first forward position corresponding with a closed and locked condition of the firearm breech bolt, to a second rearward position corresponding with an open condition of the firearm breech bolt, the operating rod apparatus comprising: a rod stem, the rod stem being operatively connected at a first forward end thereof to a piston for driving the operating rod apparatus, the rod stem having a second end thereof substantially opposite said first end; a cam associated with the second end of the rod stem; a cylinder having a passage that is in fluid communication with a pressure port located along a barrel of the firearm between a first muzzle end thereof, and a second firing chamber end thereof, the fluid communication being operative to admit propellant gasses of the firearm into the cylinder forward of the piston; an operating tube that is in sliding engagement with the rod stem, the operating tube having a forward first end and a second end substantially opposite the first end, the second end of the operating tube being operatively connected to a bolt carrier mechanism of the reloading firearm; a rod sear that is movable between a first position that constrains movement of the operating tube, and a second position that frees the operating tube to translate; an elastic bias that urges the rod sear into the first position thereof, and is overcome by the action of the cam associated with the second end of the rod stem, said cam displacing the rod sear into the second position thereof; and a return spring biasing the operating rod apparatus towards the first forward position thereof.
2. 2 . The operating rod apparatus according to claim 1 , further comprising: the operating tube comprising a tube wall, the tube wall having one or more substantially longitudinal slots formed therein, wherein at least a portion of the cam associated with the second end of the rod stem is received in the one or more substantially longitudinal slots, and the cam is guided by said one or more substantially longitudinal slots as the rod stem slidably engages with the operating tube.
3. 3 . The operating rod apparatus according to claim 2 , further comprising: the rod sear having a rod catch that is received in a sear opening of the operating tube as the rod sear is in the first position thereof, the rod catch restraining the operating tube in its forwardmost position; and the rod sear further having a cam follower that extends into the one or more substantially longitudinal slots, wherein the cam acts on the cam follower to move the rod sear into the second position thereof at a predetermined position of longitudinal displacement of the cam.
4. 4 . The operating rod apparatus according to claim 1 , further comprising: an elastic spring positioned and operable to bias the rod stem away from the operating rod tube towards a first forward position of the operating rod apparatus.
5. 5 . The operating rod apparatus according to claim 4 , wherein the elastic spring is received within the operating tube.
6. 6 . The operating rod apparatus according to claim 5 , wherein the elastic spring is a helical coil elastic spring having opposed first and second ends, and further includes at least one end plate, said at least one end plate connected with either the first or the second end of the helical coil elastic spring, the at least one end plate being perpendicular to a longitudinal axis of the helical coil elastic spring.
7. 7 . The operating rod apparatus according to claim 6 , further comprising a guide rod extending forward from the rearward position of the operating rod apparatus, and substantially coaxial with a longitudinal axis of the operating tube; the return spring comprising a helical coil spring mounted around and supported by the guide rod; the operating rod apparatus having an axial passage at least partially therethrough having clearance to admit the guide rod, wherein the second rearward position of the operating rod apparatus is defined by the second end of the rod stem contacting a forward first end of the guide rod.
8. 8 . An operating rod apparatus for a reloading firearm, the operating rod apparatus being translatable from a first forward position corresponding with a closed and locked condition of the firearm breech bolt, to a second rearward position corresponding with an open condition of the firearm breech bolt, the operating rod apparatus comprising: a rod stem, the rod stem being operatively connected at a first forward end thereof to a piston for driving the operating rod apparatus, the rod stem having a second end thereof substantially opposite said first end; a cam associated with the second end of the rod stem; a cylinder having a passage that is in fluid communication with a pressure port located along a barrel of the firearm between a first muzzle end thereof, and a second firing chamber end thereof, the fluid communication being operative to admit propellant gasses of the firearm into the cylinder forward of the piston; an operating tube having a forward first end that is in sliding engagement with the second end of the rod stem, a second end of the operating tube being substantially opposite the first end, the second end of the operating tube being operatively connected to a bolt carrier mechanism of the reloading firearm; a helical coil spring received within the operating rod tube, positioned and operable to bias the rod stem away from the operating rod tube towards a first forward position of the operating rod apparatus; a rod sear that is movable between a first position that constrains movement of the operating tube, and a second position that frees the operating tube to translate; an elastic bias that urges the rod sear into the first position thereof, and is overcome by the action of the cam associated with the second end of the rod stem, said cam displacing the rod sear into the second position thereof; and a return spring biasing the operating rod apparatus towards the first forward position thereof.
9. 9 . The operating rod apparatus according to claim 8 , further comprising: the operating tube comprising a tube wall, the tube wall having one or more substantially longitudinal slots formed therein, wherein at least a portion of the cam associated with the second end of the rod stem is received in the one or more substantially longitudinal slots, and the cam is guided by said one or more substantially longitudinal slots as the rod stem slidably engages with the operating tube.
10. 10 . The operating rod apparatus according to claim 9 , further comprising: the rod sear having a rod catch that is received in a sear opening of the operating tube as the rod sear is in first position thereof, the rod catch restraining the operating tube in its forwardmost position; and the rod sear further having a cam follower that extends into the one or more substantially longitudinal slots, wherein the cam acts on the cam follower to move the rod sear into the second position thereof at a predetermined position of longitudinal displacement of the cam.
11. 11 . The operating rod apparatus according to claim 8 , wherein the helical coil spring has opposed first and second ends, and further includes at least one end plate, said at least one end plate connected with either the first or the second end of the helical coil elastic spring, the at least one end plate being perpendicular to a longitudinal axis of the helical coil elastic spring.
12. 12 . The operating rod apparatus according to claim 11 , further comprising a guide rod extending forward from the rearward position of the operating rod apparatus, and substantially coaxial with a longitudinal axis of the operating tube; the return spring comprising a helical coil spring mounted around and supported by the guide rod; the operating rod apparatus having an axial passage at least partially therethrough having clearance to admit the guide rod, wherein the second rearward position of the operating rod apparatus is defined by the rod stem impacting a forward first end of the guide rod.
13. 13 . An operating rod apparatus for a reloading firearm, the operating rod apparatus being translatable from a first forward position corresponding with a closed and locked condition of the firearm breech bolt, to a second rearward position corresponding with an open position of the firearm breech bolt, the operating rod apparatus comprising: a rod stem, the rod stem being operatively connected at a first forward end thereof to a piston for driving the operating rod apparatus, the rod stem having a second end thereof substantially opposite said first end; a cam associated with the second end of the rod stem; a cylinder having a passage that is in fluid communication with a pressure port located along a barrel of the firearm between a first muzzle end thereof, and a second firing chamber end thereof, the fluid communication being operative to admit propellant gasses of the firearm into the cylinder forward of the piston; an operating tube having a forward first end that is in sliding engagement with the second end of the rod stem, a second end of the operating tube being substantially opposite the first end, the second end of the operating tube being operatively connected to a bolt carrier mechanism of the reloading firearm; a rod sear that is movable between a first position that constrains movement of the operating tube, and a second position that frees the operating tube to translate; an elastic bias that urges the rod sear into the first position thereof, and is overcome by the action of the cam associated with the second end of the rod stem, said cam displacing the rod sear into the second position thereof; and a return spring biasing the rod stem towards the first forward position of the operating rod apparatus.
14. 14 . The operating rod apparatus according to claim 13 , the return spring acts on the second end of the rod stem to bias the operating rod apparatus towards the first forward position thereof.
15. 15 . The operating rod apparatus according to claim 13 , further comprising a guide rod extending forward from the rearward position of the operating rod apparatus, and substantially coaxial with a longitudinal axis of the operating tube, the return spring comprising a helical coil spring mounted around and supported by the guide rod.
16. 16 . The operating rod apparatus according to claim 14 , further comprising the operating rod apparatus having an axial passage at least partially therethrough having clearance to admit the guide rod, wherein the second rearward position of the operating rod apparatus is defined by the second end of the rod stem impacting a forward first end of the guide rod.
17. 17 . The operating rod apparatus according to claim 13 , further comprising: the operating tube comprising a tube wall, the tube wall having one or more substantially longitudinal slots formed therein, wherein at least a portion of the cam associated with the second end of the rod stem is received in the one or more substantially longitudinal slots, and the cam is guided by said one or more substantially longitudinal slots as the rod stem slidably engages with the operating tube.
18. 18 . The operating rod apparatus according to claim 17 , further comprising: the rod sear having a rod catch that is received in a sear opening of the operating tube as the rod sear is in first position thereof, the rod catch restraining the operating tube in its forwardmost position; and the rod sear further having a cam follower that extends into the one or more substantially longitudinal slots, wherein the cam acts on the cam follower to move the rod sear into the second position thereof at a predetermined position of longitudinal displacement of the cam.

Description

STATEMENT OF GOVERNMENT INTEREST The inventions described herein may be manufactured, used and licensed by or for the United States Government. BACKGROUND OF THE DISCLOSURE Field of the Disclosure The instant disclosure relates to the field of armaments and more particularly to a firearm that limits the exposure of a warfighter to toxic exhaust gasses from the weapon when the weapon Is used in connection with a noise and/or flash suppressor. Brief Description of Related Art The operation of a firearm expels a projectile from the muzzle of the weapon under the pressure of rapidly combusting and expanding propellant gasses. To illustrate one particular application, involving one particular type of firearm, consider the gas-operated reloading type. Referring to FIGS. 8A, 8B, and 8C, interchangeably as the context will readily admit, illustrated is a sequence of operation for a gas-piston type reloading weapon, generally 10. This type of firearm cycles the weapon using energy derived from propellant gasses 18 in the firing chamber 32 and barrel 14. A bleed port 12 is located along the barrel 14. As the fired projectile 16 proceeds through the barrel 14, it unmasks the bleed port 12, for example as shown in FIG. 8B. The propellant gasses 18 driving the projectile 16 are admitted via the bleed port 12 into a cylinder 20. The propellant gasses 18 act on a piston 22, driving it rearward on the weapon 10. The piston 22 is connected to the bolt carrier 24 by a rod 26, and the bolt carrier 24 is likewise displaced rearward. The rearward motion of the bolt carrier 24 first unlocks the bolt 28, for example by rotating the bolt 28 through a cam action upon the bolt 28 by the bolt carrier 24. Continued rearward motion of the bolt carrier 24 together with the bolt 28 extracts the spent cartridge 30 from the firing chamber 32. Once clear of the firing chamber 32, the spent cartridge 30 is ejected through an ejection port 44. Continuing pressure of propellant gasses 18 and/or rearward inertia of the piston 22, rod 26, bolt carrier 24 and bolt 28 continues to move the bolt assembly rearwards to clear the space above the magazine 34. In the position of FIG. 8C, the projectile 16 is beyond the muzzle 36 of the barrel 14, and simultaneously, the breech bolt 28 is open at the firing chamber 32, which vents the pressure of any residual propellant gasses 18 within the combined barrel 14, cylinder 20 and firing chamber 34 to atmosphere. The combined piston 22, rod 26, bolt carrier 24 and bolt 28 have moved to the rearward extent of their range of motion, which has the effect of compressing return spring 38. With the bolt 28 clear of the top of the magazine 34, a magazine spring (not shown) raises a new cartridge 40 to the top of the magazine 34. The force of the compressed return spring 38 drives the bolt 28 and bolt carrier 24 forward. The bolt 28 strips the new cartridge 40 from the top of the magazine 34, and seats the new cartridge 40 in the firing chamber 32. The bolt carrier 24 locks the bolt 28 with the cartridge 40 in the firing chamber 32. The hammer and/or trigger sear will have also been reset by the rearward motion of the bolt 28 as well. The weapon 10 is now in battery and ready to fire again. While the trigger 42 remains depressed, the weapon 10 will fire another round automatically if in an automatic mode, or amid a burst in a burst-fire mode. If in a semi-automatic mode, the weapon 10 will fire another round by a subsequent pull of the trigger 42. The reloading cycle thereafter repeats with each round fired, until the magazine 34 is exhausted. The propellant gasses 18 unavoidably include constituents which may be harmful to a warfighter. Among these, the products of combustion will include carbon monoxide (CO), ammonia (NH3), and hydrogen cyanide (HCN). Even brief exposures to CO at elevated concentrations impairs the blood's capacity to transport oxygen. Exposure to ammonia (NH3) gasses presents immediate and significant operational issues, by generating eye, nose and throat irritation. Short duration of exposure to HCN generates eye irritation, breathing difficulty, headache, nausea, and vomiting. Propellant gasses will also necessarily contain aerosolized metals, including Copper (Cu), Zinc (Zn), Bismuth (Bi), and Lead (Pb), each of which are primary toxins. Exposure to these aerosolized metals has been termed “Metal Fume Fever”, owing to the flu-like symptoms manifest among individuals having experienced repeated and/or prolonged exposure. At least one pathway for the exposure of the propellant gasses to the warfighter is the open breech of the firearm. The breech is immediately adjacent to or at least in close proximity with the warfighter's face, nose and mouth. Moreover, the breech is opened after each and every round fired. These weapons achieve rates of fire in a range of up to approximately 750 rounds per minute. As firearms and ammunition are developed to higher stopping power and/or muzzle velocities, the