The Bushmaster Arm Pistol
By Randy Chaberlain
In the 1960’s, the US Air Force started a project to look for a new air crew survival weapon that could be used if a crew member needed to eject from a B-58 bomber in hostile territory and escape to safety.
This weapon needed to be reliable and compact enough to fit in the cramped escape capsule of a B-58. It also needed to be powerful enough to hit targets at a distance. Several weapons were piloted throughout this program, including the Colt IMP-221 but the USAF closed the program after deciding they didn’t need a new weapon after all.
the Colt IMP-221, photo courtesy of GUNs.com
Then in 1972, Mack Gwinn Jr., a retired and decorated U.S. Army Special Forces veteran with seven deployments to Vietnam, acquired the patent rights to the Colt IMP-221, a stockless, rifle caliber pistol that failed the B-58 pilot program.
Photo courtesy of American Rifleman.org
In Vietnam, Gwinn used a Stoner 63A rifle, but he wanted to build a long stroke gas piston rifle, inspired by Kalashnikov and known to be reliable. He also wanted the weapon to have characteristics like an AR15, which were cost affordable and more familiar to the civilian market.
This inspired Gwinn to start the Gwinn Firearms Company, and the outcome was two guns, a rifle and pistol that were both built with the same concept.
Then in 1973, a company named Quality Parts made an offer and purchased Gwinn Firearms Company. They rebranded, naming the two weapons the Bushmaster Assault Rifle and the Bushmaster Arm Pistol. This acquisition made the Bushmaster name a major player in the US Firearms market.
The Bushmaster Arm Pistol is a rudimentary weapon with a threaded muzzle and 11.5-inch barrel that shoots 5.56 x 45mm rounds, feed by a standard AR-15 STANAG magazine.
The upper and lower receivers are cut from blocks of aluminum, and the remainder of the parts are steel. The semi-automatic action is locked by means of modified M16 rotating bolt system with a cam raceway machined into the wall of the aluminum upper receiver.
A Pistol grip and flash suppressor are standard M16 components and charging handle cycles with the action. The sights are adjustable with a fixed front sight and corresponding notch in the rear. The weapon came in three finishes: parkerized, electroless nickel, matte nickel.
The firearm has a loaded weight of 5.25 lbs. The most unique feature of the Bushmaster Air Pistol is a rare ambidextrous design, with an upper receiver that swings side to side to the shooter’s preference.
This flexibility makes it easier to tuck the end of the weapon into the bicep when firing and allows for both right- and left-hand fire. The sights also rotate to the left and right to accommodate the orientation of the receiver.
Safety features won’t allow the weapon to fire unless it’s locked in one direction or the other, or it’s locked in the middle. The weapon also has reversable sling mounts both front and rear.
Safety features for the Bushmaster Arm Pistol depend on which production period the weapon was made in. The earliest batch of weapons had a rotating level similar to the AR-15. The second run had a slide level located at the head of the trigger guard, making it easy to change with the trigger finger. The newest batch of firearms produced had a rotating safety level built into the rear of the lower receiver.
photo courtesy of laststandzombieisland
By 1984, the weapon was in production for approximately 6 years. There weren’t a lot of black gun enthusiasts to buy such a weapon, and the market wasn’t as big as it is today. Only 2100 Arm Pistols were made before production stopped around 1990.
The story of the Bushmaster Arms Pistol doesn't end there. In 2024 Hydra Weaponry, founded by the inventor Mack Gwinn, announced the return of the design in the BMP-23 pistol.
While researching this firearm I checked the Hydra website and they had 6 in stock.
Overall, the weapon may be inaccurate and unpractical, but the Bushmaster Arm Pistol is a fun and rare gun to shoot. I acquired my Bushmaster Arm Pistol at the Phoenix Gun Show back in December.
About the author:
Randy has been a decades long member of the NRA, the Civilian Marksmanship Program and Washington Arms Collectors; he began collecting weapons in the 70's and has owned more than 500 weapons including the subject gun above. He will continue to contribute his vast knowledge of surplus and collector weapons.
