The Gwinn/Bushmaster Armpistol

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).


20 thoughts on “The Gwinn/Bushmaster Armpistol

  1. cam

    I actually have one of these. serial number 2100 series. Its a civilian model and has only the one safety above the pistol grip. I paid 600 for i a couple of years ago. Its really a cool conversation piece but as far as an effective weapon i have my doubts as the ergonomics of the thing suck. I havent fired it more than a few dozen times so i may just need more practice to improve my results. My favorite thing about it is the massive fireball it spits when you shoot it at night. There is little info about them on the net so correct me if im wrong but I believe i saw somewhere that the design was meant for air force pilots who at the time were stuck with puny .22 caliber survival rifles if shot down. The one handed rotating grip seems perfect to spray a tree line down with fire if one was slowly decending in an ejection seat or for a chopper pilot to spray out the side window in a hot lz while keeping one hand on the stick. I dont know if its possible to fly a chopper one handed but those scenarios seem plausible to me.

    1. Hognose Post author

      Actually USAF pilots had a .22 Hornet/.410 shotgun over-under in their survival kit, and a revolver or .45 in a holster on the person or on the survival vest. USN/USMC pilots just had the handgun. Helo pilots often carried a CAR-15 or M16 and occasioanlly fired it out the crew door just to make noise.

      I’m not aware of any incident in which any of these weapons let a solo downed pilot shoot his way out of captivity in Vietnam, but it might have happened. I do recall hearing of cases from WWII.

      1. Hognose Post author

        And yes, the original idea was for an aircrew survival weapon. You probably did alright buying it for $600. In the long run, the weapon will be valuable because 1) as you note, it is an odd conversation piece, 2) production was low for a 5.56 semi weapon, and 3) it was AFAIK Bushmaster’s first product.

  2. cam

    I figured i got a good deal on it cause i broke the sear in it shortly after buying it. Unfortunately that is one of the only parts in the FCG that isnt AR15 and had to pay 300 for a lower i found with all the parts. It was the only replacement parts i could find. Interesting fact is the ATF considers the upper on these to be the actual weapon not the lower like on AR15s.

    During my search i found a few old discussion sites in which people said there is a guy that has been at bushmaster since the beginning who actually has a private stash of parts for them but i didnt try to contact him. Bushmaster itself of course no longer has any parts for them.

    Ive got a stack of papers that the fellow i purchased it from gave me that went into great detail about the military trials and how badly the weapons performed during them. If im not mistaken their was something in there about the Colonel that ordered it getting in trouble over it for some reason as well. I am sure it said that 2100 of them were made for the military though i dont know if they were actually delivered. I remember this because at first i thought i got an example of a gun that only 2100 were made and was a little disappointed when i noticed it said 2100 made for the military. I believe the military also had a different finish.

    I didnt really pay much attention the paperwork at the time as i wasnt as into the history of guns as i am now. Ive always been a gun nut but a gun nerd like Ian over at Forgotten Weapons would appreciate documentation like that more than i did when i acquired it. Youll have to forgive me for not having this info in front of me. Like i said i only recently graduated from gun nut to gun nerd and started caring about things like paperwork. Ill try and find it and send you a copy if your interested. Hopefully it didnt get thrown away.

    1. Hognose Post author

      Very good, yes we’d love to see that info, so would Ian. He has more of a soft spot for orphan guns than I do, I think.

      Isn’t the sear a pretty simple part that could be bandsawed from bar stock and drilled for the pin?

      I’m really surprised to hear of 2100 made for the military. Still, it’s possible. In SF we bought a couple thousands AKMS rifles in the 1980s and I’ve never seen documentation of that, even though I was there when they were delivered!

      1. cam

        Someone who can is good with metal work could probably make a sear easy enough. I would think there is a little more to it than sawing and drilling. Im not very knowledgeable in metal working though.

        I looked on GB last night after writing this and there is actually one for sale on there with me being the only bid 20 bucks. Just my luck I spent 300 for a whole lower and later find one for 20 bucks. Its been repaired by braising but i actually did the same with the one i broke and it seems to be sturdy enough to hold up though i havent tried it since fixing it.

        Apparently every model had differences in the sear. The two i have are from early models and this one seems to be made a little better. It looks different than the one my early model came with. Looks like Bushmaster was improving the design of problem parts as it evolved. Im trying to pick it up for a spare. Here is the item number and you can tell me if it looks easy to make. 301864971

        As far as the paperwork its gonna take a few days of searching. We moved a week ago and pretty much everything i own is still in boxes but if i cant find it the man i brought it from can probably help with obtaining it again. Hes as big a gun nerd as Ian is mine were photocopies which means he probably still has the original.

          1. cam

            Ye i i noticed that one and its surely not original. Thats not the original brake or pistol grip. Ive got the original but its cracked so mine also has the a2 type pistol grip on it right now. Also it looks like someone tried to give it a camo paint job at one time using what looks to be ferns as the pattern. Could just be the way the light is hitting it but dont think so.

          2. Hognose Post author

            The A1 grips are fairly common and come up on GB and on the retro forum at ARFcom and on Retro Black Rifle a lot. They’re one of the few A1-specific parts that hasn’t seen the supply completely dry up over the last two years.

            There’s a lot of information lacking on these. I suppose I need to check my Small Arms Review index to see if someone wrote it up there. I do have all the old SOF magazines but they’re not organized at all.

          3. cam

            There is also another example on GB that is a no reserve bid someone could pick up at a steal that looks to be complete except for the trigger guard.

          4. cam

            The original grips for these have a small b inside of a circle on them. A purist would want to find one of them. I have an a1 type for it but havent taken the time to install it.

            I think my wife may have thrown away the documents i was talking about. Ive looked high and low but have had no luck. I am however 100% sure it said that 2100 were produced for the military and that the Colonel that placed the order got in a heap of trouble for doing so. Think it said he got demoted over the fiasco. Like i said just cause they got made doesnt mean they got delivered. Im gonna give the man i got it from a call and see what he says.

  3. cam

    Another piece of info is later models had a last round hold open. and different sights. I know because the lower i was talking about has the hold open part where my early version does not. The sights were also slightly improved.

    Also if you look at the picture of the airforce trials model has no safety inside the trigger guard and is nickel finish. It doesnt match up with the one listed on GB as being an air force model. The inside the trigger guard saftey was on the 2nd generation civilian models. I guess the one listed on GB could be a prototype but doesnt make much sense to me to have features on a prototype that according to what i found were not added till the mid 70s. That fact added to the fact that it doesnt look to be nickel matte finished make me wonder.

  4. cam

    Another thing i just noticed about the supposed air force pistol in your story is that it is a top cocker where as the air force trial variant on bigger hammer were side cockers. Im very suspicious of that guys description. Do you know if its title 2. Im thinking that bushmaster may have restarted the serial numbers when they switched to later models.

  5. cam

    I took a shot in the dark and emailed Mack Gwinn Industries in hopes someone could help verify. I also saw a registered full auto example on gunsamerica that was going for 13k a few months ago.

  6. cam

    after sifting through about 20 pages of google search i found this a fellow talking about being issued one that his armorer said was an experimental design but then never seeing one again.

    Also found this thread on that has a picture of an add for one that also says their was and article about the armpistol in the summer 1976 issue of SOF magazine. It also has the article scanned into the thread that should keep you from having to dig through your unsorted stash. Scroll down a little to see the add and the article. It aint about the military use but it is got all kinds of info about it from back in the day.

  7. darthny

    I have one of these, serial J00282. Bought if from a fellow soldier when I was in the Army for $400. Came with no rear or front sight but that never stopped me from having a lot of fun with it. Over time I lost the original charging handle which I never liked much as it never sat tightly and would bind when I tried to chamber a round. I just recently fabricated one from a machine screw and a type of coupling nut. After some grinding and filing so it would fit into the original chaging handles slot, it works better than the original ever did and it doesnt look bad. Mine may not be original and thats fine with me as I have no plans on selling it. Have plans to add a laser to the gas tube using a rifle barrel mount. As it just clamps on it wont alter the weapon any but should make targeting fast and easy. May even add a foregrip to improve handling.

    1. Hognose Post author

      Just be aware that as it sits, it’s a “pistol” — adding a foregrip might make it “Any other weapon” under ATF regs. There are a lot of people in ATF who would rather pursue arcane technical violations like that than chase dangerous violent criminals. (And there are a lot who would rather bust the violent criminals. Guess which ones get the promotions?)

      1. darthny

        Thats something worth considering. Thanks for the headsup. Ill definately check into it because the extra control from the foregrip would make shooting more enjoyable.

        1. Hognose Post author

          The “official” way to shoot an Armpistol is with the pistol grip in your strong hand, and canted outboard relative to the vertical axis of the gun (that runs through the magazine). So for a right-hander the grip is swung out to the right, for a southpaw, the other way around. Then you take your weak hand and press the receiver against the inside of your strong arm. This kind of locks the gun to your strong arm and it’s accurate enough that way, either using tracers for pointed fire or the factory pistol-type sights (which you’ve mentioned are absent from your gun) for aimed fire.

          This is a weapon which would really benefit from some of the technology in red dots and lasers that was only developed after it was discontinued. Problem for Bushmaster is, 1, guys like you who don’t just think it’s neat but actually buy one are rare, and 2, there’s nobody at Bushmaster that remembers the guns the company was making 25 years ago. Heck, no one at Bushy remembers the guns they were making 25 months ago — those guys are all working at Windham Weaponry (and they still don’t remember the Armpistol).

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