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AO Thompson M1SB

Whilst browsing around the Auto-Ordnance site, I came upon their <broken link removed> :


It is basically their semi-auto M1 with a 10½" barrel. It looks pretty interesting.

Anyone have experience with these? Good, bad, or ugly?

No experience, but the short barrel matches the original TSMG specs. (Note: very few receiver parts interchange between a Kahr or West Hurley semi and a GI M1 or an original 1921/27/28, largely because of the redesign required to go closed-bolt and otherwise comply with "not readily convertible to full-auto." This is why original 1927 semis are cheap: they have all the arse-pain of NFA MG since they were factory converted from full-auto 1921s and "once MG always MG," but none of the rock-n-roll fun.)

DB, Thompson nut who has owning a live Colt 1921AC on his bucketlist
I had one about ten years ago and it was very finicky with magazines. You have to modify military surplus magazines in order for them to work in the AO Thompsons. The magazine catch/release is different. You have to dremel the hole on the surplus magazine for it to work in the AO Thompson. If you do it right, they work fine. Even the AO supplied magazines were problematic. I also had an extractor break. Once I got the magazines tuned so to speak it ran fine. It was an expensive plinker though so I sold it. Mine was an alloy frame and receiver version. Much lighter than original but the internals were the same. I had also SBR'd it as they did not offer them from the factory like they do now.
The alternate option is to replace the mag catch with modified GI--if I had budget for a Thompson, that's the direction I'd go, in no small part because modding the mags for semi guns makes them unusable in the originals.

Dunno if he's still in business, but back in college when my Thompson geekout first started, my very first move other than taking it out for a "diagnostic" shoot would have been to ship the gun off to Paul at Diamond K and the drums off to Merle "Drum Doctor" Bitikofer for top-to-bottom tune-up.


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