This weapon is one of those oddities that makes you go, “Neat… but … why?” We were reminded of it by Frank Goepfert listing what he believes is an original prototype, possibly the original prototype, on GunBroker.
Here is part of what his blurb says:
You are bidding on a very rare original Gwinn armpistol. These are little more than a foot note in small arms development history and a very collectible item. This gun was developed due to a need for a small sub machine gun with the capabilities of the M16. This gun uses the same mags, ammo and shares many common parts with the m16.
From what little I have been able to find about these, only very few were manufactured and deployed with US special forces. Some semi auto variants were later made for civilians after Gwinn was purchased by Bushmaster. This is NOT what this one is. This gun is one of the original Gwinn factory machine guns. This is SN 101. I have no idea what number production started with, but it stands to reason it was likely not “1” and this is a very very early gun. This has been with the same collector for many years, has the original finish and is for all purposes as new.
There are several inaccuracies in there. While some SF or SOF guy may have shot Gwinn’s gun, particularly some Reserve or Guard guy, the implication that the weapon was every adopted or deployed by SF or any SOF element is not true. The Air Force tested something similar (the IMP) as an aircrew’s defensive weapon, and found it interesting but impractical. When Bushmaster, then based in Portland, Maine, acquired Gwinn, they produced the weapon as “the Bushmaster” and promoted it heavily. They also made rifle versions, before dropping these piston-driven weapons and turning to AR-15 clones.
One interesting feature of the weapon Goepfert is offering is the location of the safety. It’s generally understood that the early Gwinns are the ones with the safety/selector on the forearm above the pistol grip. It was later relocated to the butt area to make more direct use of M16 surplus parts. But this weapon has the selector located in the butt area, and a separate sliding fire-safe safety, a bit like an inverted tang safety with fire forward, inside the trigger guard in a natural position for someone who knows the M1 rifle. (It’s almost exactly like a PPSh safety, actually).
The later Bushmaster weapons were mostly semiautos, but production can’t have been very high. The weapon is peculiar enough to have been a very hard sell into the basically conservative gun-buying public.
We shot one of the semi-auto Bushmaster examples a long time ago (1980s) and remember it as a lot of fun. After first getting used to it is is possible to hit targets solidly at CQB ranges without using the rudimentary pistol sights. With the sights, and by pressing the receiver of the gun against the bicep with the off hand, it’s a 200-meter weapon. With a modern optical sight like an ACOG you could probably have successfully shot the 300-meter Army Trainfire qualification range of the time (although probably not the Marine 500-yard QD qualification). Like most ARs, piston or not, fed from good mags it was reliable.
The Armpistol was something that actually had a lot of CQB potential. Nobody would give up his 10.5″ M4 or his DOE 9mm for it now, but it might have changed the course of history, if some service could have overcome its sheer weirdness.
At that time, we were doing CQB with .45s and there was a major debate on as to whether it could be done safely with CAR-15s or whether we’d need to fully commit to an intermediate weapon, like an MP-5. Around that time, guys who did more CQB than we did went to the MPs, but in time, short and reliable 5.56 carbines replaced both pistol-caliber submachine guns and pistols themselves as first-choice weapons for room clearing and hostage rescue. Pistols remained preferred for some situations (highly constricted linear targets) but for most purposes, the accuracy of a carbine with a red dot sight trumps both sighted and instinctive fire. At least when human life is at stake, and non-targets are mixed in with the tangos.
This website has a little bit of info on the Gwinn/Bushmaster armpistol, including pictures of a few variants and a copy of the Bushmaster-era manual. It was also covered in Soldier of Fortune (we’ve really got to organize our collection… ) and Jane’s Infantry Weapons during the period that both Gwinn and Bushmaster were actively promoting it.
One historical footnote about the Gwinn: it was probably the first successful attempt to marry a gas piston to the AR bolt / carrier system.
At this time, Goepfert’s gun hasn’t been bid very high ($3k when his buy-it-now is near $20), and it’s an absolute auction, but the beady-eyed pros like us usually only hit auctions in the 11th hour, so maybe he’ll make his estimate. There have been some wild auctions lately (translation: we and our friends have been outbid).