Bushmaster Assault Rifle USAC-556
Printed From: AMT Guns information
Category: Auto Mag Pistol
Forum Name: Other non AMT weapons
Forum Description: Any other rare unusual weapon...
URL: http://www.amtguns.info/forum_posts.asp?TID=3003
Printed Date: 26 Mar 2026 at 10:05pm
Software Version: Web Wiz Forums 12.06 - https://www.webwizforums.com
Topic: Bushmaster Assault Rifle USAC-556
Posted By: Luc V.
Subject: Bushmaster Assault Rifle USAC-556
Date Posted: 10 Jul 2025 at 5:55pm
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Bushmaster Assault Rifle USAC-5.56 This is a rifle I have in my collection from the very early
days of the Bushmaster brandname. There is very little to find on the internet about this rifle. So far I found that the original designer was Mark Gwinn,
and made it under the brandname Gwinn firearms. He probably sold his concept to Bushmaster, but it looks as
they didn’t produced much of them. At some point it was re-designed to the “bushmaster pistol”.
This was same gun without the shoulderstock but with some kind of rotating pistolgrip and shorter barrel. I always found this a very interesting concept, sort of a
mix of the AK47 and the M16. Pretty simple or rough but it works... Front part (or upper) of the rifle use the AK47 type of gassystem, with
fixed gas-piston on the boltcarrier. The bolt and lower uses the M16 parts, To be correct, the
bolt is very simillar to the M16 but not exactly the same, the rotation pin is
at a different angle. The lower parts (trigger, sear, etc) are the same as the
M16. Anyhow, if anyone has more info about this rifle, please
post here. Thanks.
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Replies:
Posted By: Luc V.
Date Posted: 10 Jul 2025 at 5:58pm
Some more info from the original manual:   |
Posted By: RangerJim
Date Posted: 10 Jul 2025 at 10:32pm
I swear I have seen this rifle in an old issue of Soldier of Fortune magazine. And speaking of that mag, I just got the August 1971 issue of Guns magazine that introduced the MAC M10 and M11 Ingram to the world. The author of the article: Robert K. Brown, the creator of the SOF magazine!
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Posted By: Stainless Magnum
Date Posted: 12 Jul 2025 at 5:44pm
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Could this have indirectly (or directly) influenced this: https://www.youtube.com/watch?v=8I8Mm7b1Esk  ------------- "Feo, Fuerte, y Formal" John Wayne, on how he would like to be thought of. Translation: Ugly, strong, and dignified. |
Posted By: Luc V.
Date Posted: 13 Jul 2025 at 7:42am
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Hi Jim, If I'm not mistaken, that rifle should be from around late '70s or early 80s. I bought it in 1980... If you find the article, please post it if possible. For me that Deawoo K2 looks more similar to the FN CAL. That is the Original name in French: "Carabine Automatique Leger". In English you should read it backwards as in Light Automatic Carbine. CAL 223 Does not stand for caliber 223, (but it is in fact) That is also a very rare carbine from the Belgian FN Herstal factory. I might do a post on this one later on...    Back to the Bushmaster USAC, this has no adjustable gasregulator and the gasblock is just pinned to the barrel. However it has an ingenious way to strip the boltcarrier from the gaspiston no tools needed ;-) The upper receiver is sheetmetal with spotwelded rails for the boltcarrier to run on. The boltcarrier is simply a bar of flat steel with a big lug welded on in which the bolt can ride /rotate. I try to strip it down later this week and post some more pictures here.
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Posted By: Luc V.
Date Posted: 13 Jul 2025 at 3:51pm
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One more nice detail about the selector: B for Bushmaster:  |
Posted By: Rumore
Date Posted: 13 Jul 2025 at 5:06pm
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I would like to see a pic of the underside of the bolt carrier. Tony ------------- Run it up, until you blow it up, then back it down a bit. |
Posted By: RangerJim
Date Posted: 13 Jul 2025 at 5:24pm
| To my eye, the K2 reminds me a little of the Stoner63. Another very cool rifle (system actually-since it had several versions including a belt fed MG). |
Posted By: Stainless Magnum
Date Posted: 13 Jul 2025 at 5:53pm
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I agree with the Stoner resemblance. ------------- "Feo, Fuerte, y Formal" John Wayne, on how he would like to be thought of. Translation: Ugly, strong, and dignified. |
Posted By: RangerJim
Date Posted: 14 Jul 2025 at 1:21am
Luc, I knew I had seen your rifle in an old magazine. Scored some info on both of the above rifles. The USAC-556 was featured in Soldier of Fortune magazine, May 1979 on page 61. And the FN CAL556 is featured in an article, “Belgium’s New Carbine” in the December 1985 issue. You can find the articles on archive.org and search for SOF magazine. But here are the pages you would be interested in. Jim  |
Posted By: Luc V.
Date Posted: 14 Jul 2025 at 1:31pm
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Jim, Thanks for the info, I'll check it out!
Tony, picture of the carrier underside down below. (PM if needed more details) Hereby some more information about the USAC rifle to field strip: Use the tip of cartridge to push the retention ring for the recoilspring into the gastube,  Now pull the clip holding this ring in place out (upwards).  Rotate this ring upside-down (180 degrees) so the flat side is on top and inline with the boltcarrier.  Now you can slide the whole carrier to the rear, pull the cocking handle out, and pull the assembly out of the "upper".  And here's the bolt and carrier completely stripped, all done with the tip of a cartridge!  This looks a very simple but smart way to produce this gun, just some flat bars of steel welded together. ( Max Gera would have hated it
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Posted By: jw4570
Date Posted: 22 Aug 2025 at 1:53am
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I remember these being advertised. I have seen a couple around, but too much money for the novelty for me. Now for the FAL variants. I have several Semi versions on DSA receivers. I don't have any original (Select Fire). Most of mine are custom, but I have a very early FN STG Austrian kit before Steyr took over built up. Thanks for sharing the Bushmaster, it was a trip down memory lane.
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