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Posted: 7/24/2026 11:10:28 AM EDT
https://www.youtube.com/watch?v=wKTlYPQF2KI Kinetic Crossfire Thompson FRT #thompson #frt #tommygun https://www.kinetic-crossfire.com/ https://www.youtube.com/watch?v=wKTlYPQF2KI This has to be old news....and if it is, I apologize. If it's not, what's the skinny on function? Finicky or easy? Too bad semi Thompsons aren't cheap like AR's. |
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Old news. Check out the Machinegunboards. The semi auto section has a really good write up about trying to get this to work. There is also a youtube series on making the semi Thompson work as well including with the FRT. Overview. It's an idea that people want but it's not quite there yet. It's also only safe or full fun. No option to run semi. |
 Thompson FRT in action This is the Kinetic FRT in my Kahr Thompson. Runs great with 20 rd stick mags and my 50 rd drum using Magtech ammo. Dropped in and ran without any mods. After reading about all the potential issues online, it was actually one of the easiest FRT builds I've done. The guy who did a 9 part series on his Kahr Thompson ended up causing many of his own issues when he installed the FRT. Trying to use lighter recoil springs, using the wrong bolt, etc. I kept it simple and had none of those problems. My gun also ran fine in semi before I dropped the FRT in. I could care less about no standard semi function, it's a subgun after all. Rate of fire is high on mine - 1047 RPM when I plugged that video into the online ROF calculator. Still pretty controllable, you can hear the hits on the steel gong at 50 yards. It's a blast to shoot, and finally makes owning a semi Thompson worth it. |
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I am trying to make my gun run. Turns out Kahr arms 1927 early builds were a bit variable in dimensions. Mine is only currently working in semi. I apparently have to file down the latch so it more fully engages the sear and does not release and cause a reset of the sear. I am confident I will get it working, just didn't plan on becoming an expert on kahr 1927s. |
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Originally Posted By JsARCLIGHT: I bought one for my 1927A1 but haven't installed it yet. They sent me a longer striker spring for free. Yes I cut the striker spring down to 19.5 cm based on their instructions. I must have gotten lucky as it ran without any further mods. I do have some concerns about the factory recoil springs losing tension quickly but it's a cheap fix to grab a new set if it happens every couple thousand rounds. |
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Originally Posted By tac556: Those seem to have a hell of a lot faster ROF than a real M1A1. I recall it being an extremely slow firing gun…Those FRT’s might be double the ROF basically. The original 21s shot at a similar ROF. The 21/28 reduced it quite a bit, and then it went back up again with the M1. The semi design uses a completely different spring setup than the originals so modifying the ROF is going to require different methods. |
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Originally Posted By TheFaz: The original 21s shot at a similar ROF. The 21/28 reduced it quite a bit, and then it went back up again with the M1. The semi design uses a completely different spring setup than the originals so modifying the ROF is going to require different methods. That doesn’t surprise me at all. I have only shot the M1A1 variant, and it was the slowest F/A that I have fired. That one came out of an LE armory, so it had not seen active duty use or real upkeep in decades I imagine. (I have never fired an M3 or M3A1, those would likely be even slower). |
a loaded gun won’t set you free, so you say…
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I installed mine into my 1927a1 SBR yesterday after this thread reminded me I had it. Took about an hour to install, mostly because the firing pin tab is purposefully made too long and you have to hand fit it to your trigger. All that means is installing the firing pin, putting your lower back on, trying to cock in the gun (it will get stuck half way), then taking it apart again and gently filing down that tab a little at a time and trying again until the bolt pulls all the way back without getting stuck. It is not as difficult as it sounds, and if an ape like me can do it you probably can. The only other "hand fitting" needed was to cut their supplied long striker spring to the recommended length. I plan to go test it this afternoon, but the action cycles smooth and I can feel the trigger resetting and the striker dropping. I forgot just how stiff the action in these semi Thompsons are, after pulling it back like 50 times yesterday function checking even wearing gloves the cocking handle chewed up my fingers. As others have said do not install the EZ Pull kit with the FRT. |
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Originally Posted By tac556: Those seem to have a hell of a lot faster ROF than a real M1A1. I recall it being an extremely slow firing gun…Those FRT’s might be double the ROF basically. Well then one needs the 1927 or 1928 type!  Edit, I guess the 1921 instead. |
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