Bushmaster Assault Rifle: A Stoner-Inspired 70s Carbine

Mack Gwinn was a US Army Special Forces officer in Vietnam (he retired from the service as a Captain) who had extensive experience carrying and using a Stoner 63A. When he returned home, he decided to get into the firearms industry. His first work was the Ranger 7, an improvement on John Foote’s FAC-70, but this did not see production. What did get into production was his Bushmaster Assault Rifle, a long-stroke gas piston rifle with an AR style bolt and fire control group, apparently inspired by elements of the Stoner. The design was sound (and fairly simple), but unfortunately the manufacturing was quite crude.

The Bushmaster was originally produced by Gwinn Firearms, until it was transferred to a company called Quality Parts, which renamed itself Bushmaster Firearms in the process. The example we are looking at today is a Bushmaster-production one. Eventually production of the Assault Rifle ceased, and Bushmaster became much better known for making AR-15 rifles. Gwinn remained in the industry, designing a number of significant items including a QD barrel system for the Browning M2 for FN, a drum magazine for the AR and Mini-14, and most recently the MGI Hydra modular barrel system for the AR.


  1. Thanks for this review. It’s an interesting design. As you indicate it’s a mix of AR-15, AR-18, and AK-47.

    I wonder if a modern made set of fire control parts would fix the failure to fire issue.

  2. Innovation at its most mashup. The fail to fire percentage is scary. If a gun of that “military format” is not much more reliable, it will die in the marketplace. Why Bushmaster did not improve the gun is a question that deserves an answer.

    • I doubt there was any real link, aside from maybe seeing pictures and reports in Jane’s. FN back in the day was pretty close-hold, and I think that the timeframe this was coming up was when the CAL was the thing they were pushing. The FNC also does not have the Johnson-esque multi-lug bolt; it’s more of a true AK-in-Western-format, just like the SIG 550-series rifles.

      It wasn’t like today, when all this information and data is out there on the internet, world-wide. You’d have to wait for someone in the gun magazine/military review field wrote a story, and then it’d be pretty low on actual information content. I don’t think that people today really appreciate just how long it took for things to disseminate, and how much outright malinformation was out there back when.

      Good grief… The amount of misinformation about the AK and its follow-ons? Yikes. Actual verifiable information on the AK-74 was almost impossible to get your hands on, when it was first out there. Today? LOL… Man, you’ve got guys in the Kalashnikov factory doing firing tests and posting real-time data about stuff. It’s nuts, when I think about it all.

    • Not a chance; this is a P.O.S. in comparison. The FNC is a product of a proficient and skilled organization, this is a cobbled up amateurish attempt. It would never stand serious consideration for any official armed organization.

      There is is misconception that by mixing previously successful designs one automatically derives a “best” solution. This is wrong right from start.

  3. “…including a QD barrel system for the Browning M2 for FN”. Did you mean to say “a QC ( Quick-Change ) barrel for the Browning M2 for FN” ? As far as I know, virtually all iterations of the M2HB / M2A1 / M2A2 with a a quick-change barrel feature are referred to by the respective manufacturers, including FN, using a QCB suffix or description.

  4. The Bushmaster that Ian really needs to do a piece on is the Arm Pistol. I’m actually surprised that he hasn’t, already–At least, there’s nothing that comes up on a search.

    Another void–The Colt IMP that the Arm Pistol was derived from. Fascinating guns–A friend had one of the Arm Pistols, back in the day. When you could get it to work, it was a hoot.

    • Colt IMP was designed originally during mid 1960s in caliber Rem..221 as an Aircrew Survival Weapon. It is covered in detail in Modern Military Bullpup Rifles by T.B. Dugelby.

      Colt brochure says:
      “Although the prototype weapon was right-handed, left-handed shooters found hey could use it effectively as right-handed. This is not true of a conventional rifle or pistol. The prototype proved to be capable of excellent accuracy and ease of holding on target.”

  5. I remember stumbling in internet long time ago (12-15 years), that they made some obscure US assault rifle, maybe even this,
    that went with serialized belt buckle and a knife, all in a kit.
    Anybody heard about it too ? I’ve searched but cannot find it again 🙁

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