Bushmaster Assault Rifle USAC-556

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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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Luc V. Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 09 Mar 2008 Location: Belgium Status: Offline Points: 1433	Post Options Post Reply Quote Luc V. Report Post Thanks(0) Quote Reply Topic: Bushmaster Assault Rifle USAC-556 Posted: 10 Jul 2025 at 5:55pm
	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.

Luc V. Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 09 Mar 2008 Location: Belgium Status: Offline Points: 1433	Post Options Post Reply Quote Luc V. Report Post Thanks(0) Quote Reply Posted: 10 Jul 2025 at 5:58pm
	Some more info from the original manual:

RangerJim Members Profile Send Private Message Find Members Posts Add to Buddy List International Auto Mag Joined: 10 Jan 2025 Location: Illinois Status: Offline Points: 88	Post Options Post Reply Quote RangerJim Report Post Thanks(0) Quote Reply 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!

Stainless Magnum Members Profile Send Private Message Find Members Posts Add to Buddy List International Auto Mag Joined: 10 Mar 2008 Location: New "Old West" Status: Offline Points: 89	Post Options Post Reply Quote Stainless Magnum Report Post Thanks(0) Quote Reply Posted: 12 Jul 2025 at 5:44pm
	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.

Luc V. Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 09 Mar 2008 Location: Belgium Status: Offline Points: 1433	Post Options Post Reply Quote Luc V. Report Post Thanks(0) Quote Reply Posted: 13 Jul 2025 at 7:42am
	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. Thanks for the reply David. 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.

Luc V. Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 09 Mar 2008 Location: Belgium Status: Offline Points: 1433	Post Options Post Reply Quote Luc V. Report Post Thanks(0) Quote Reply Posted: 13 Jul 2025 at 3:51pm
	One more nice detail about the selector: B for Bushmaster:

Rumore Members Profile Send Private Message Find Members Posts Add to Buddy List Callahan's Auto Mag Joined: 14 Nov 2008 Location: Inola, OK Status: Online Points: 524	Post Options Post Reply Quote Rumore Report Post Thanks(0) Quote Reply Posted: 13 Jul 2025 at 5:06pm
	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.

RangerJim Members Profile Send Private Message Find Members Posts Add to Buddy List International Auto Mag Joined: 10 Jan 2025 Location: Illinois Status: Offline Points: 88	Post Options Post Reply Quote RangerJim Report Post Thanks(0) Quote Reply 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).

Stainless Magnum Members Profile Send Private Message Find Members Posts Add to Buddy List International Auto Mag Joined: 10 Mar 2008 Location: New "Old West" Status: Offline Points: 89	Post Options Post Reply Quote Stainless Magnum Report Post Thanks(0) Quote Reply Posted: 13 Jul 2025 at 5:53pm
	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.

RangerJim Members Profile Send Private Message Find Members Posts Add to Buddy List International Auto Mag Joined: 10 Jan 2025 Location: Illinois Status: Offline Points: 88	Post Options Post Reply Quote RangerJim Report Post Thanks(0) Quote Reply 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