reconbob Posted March 28 Report Share Posted March 28 If you are assembling/replacing parts in a trigger frame, consider yourself lucky if it works. I just finished assembling/testing a batch of trigger frames for the blank guns and it was a long, long way from assemble and shoot. We are getting to the end of the line with many parts (Sarco no longer lists Thompson parts.) And maybe the parts out there over many years have been rejected, sold, rejected again, resold, etc. and an increasing number of them are no good. Here are some of the parts and their defects - Sear - leg that engages sear lever is too thin = sear will not drop far enough to release bolt Sear lever - leg that engages sear is not thick enough = sear will not drop far enough to release bolt Disconnector - leg that engages sear lever is too short = sear will not drop far enough to release bolt Disconnector - leg that engages sear lever is too long = disconnector will not rebound under sear lever Disconnector - arced surface that engages sear lever is too flat = disconnector will not rebound under sear lever Trigger - hole for disconnector is too high/low = sear does not function properly Rocker - height is too short/low = not tripped by bolt on semi Rocker - height is too long/high = trigger frame will not slide onto receiver when set to full auto Sear spring - can have "kink" in the coils = sear does not drop all the way and/or "two stage" pull The defects in the legs of the sear and sear lever are easy to spot if you have seen enough of them but the other parts you can't tell until you try them. Bob 1 Link to comment Share on other sites More sharing options...
TD. Posted March 28 Report Share Posted March 28 Bob, Great information. Thank you for sharing. I am not surprised the availability of useable Thompson parts is on the decline. When Auto-Ordnance (AOC) West Hurley, New York put the Model of 1928 Thompson submachine gun back in production in 1975, they thought they had plenty of surplus parts in inventory for projected production and sales. Wrong! It was not too long until their inventory of certain parts ran low or were exhausted. AOC President Ira Trast told me he initially shopped around with other vendors for Thompson parts but soon found any sizeable supplies in the USA was soon depleted. This led to AOC WH having many Thompson parts manufactured. Of course, these WH parts are usually very problematic. The so-called Russian parts kits years ago restocked the supplies for enthusiasts. It now appears the cycle has repeated itself. Can you post some comparison pictures of the defective Sear and Sear levers for all to see. This will be a big help to forum members. Link to comment Share on other sites More sharing options...
Rekraps Posted March 28 Report Share Posted March 28 1 hour ago, reconbob said: If you are assembling/replacing parts in a trigger frame, consider yourself lucky if it works. I just finished assembling/testing a batch of trigger frames for the blank guns and it was a long, long way from assemble and shoot. We are getting to the end of the line with many parts (Sarco no longer lists Thompson parts.) And maybe the parts out there over many years have been rejected, sold, rejected again, resold, etc. and an increasing number of them are no good. Here are some of the parts and their defects - Sear - leg that engages sear lever is too thin = sear will not drop far enough to release bolt Sear lever - leg that engages sear is not thick enough = sear will not drop far enough to release bolt Disconnector - leg that engages sear lever is too short = sear will not drop far enough to release bolt Disconnector - leg that engages sear lever is too long = disconnector will not rebound under sear lever Disconnector - arced surface that engages sear lever is too flat = disconnector will not rebound under sear lever Trigger - hole for disconnector is too high/low = sear does not function properly Rocker - height is too short/low = not tripped by bolt on semi Rocker - height is too long/high = trigger frame will not slide onto receiver when set to full auto Sear spring - can have "kink" in the coils = sear does not drop all the way and/or "two stage" pull The defects in the legs of the sear and sear lever are easy to spot if you have seen enough of them but the other parts you can't tell until you try them. Bob Wow, I'm glad the spare parts I have are OEM "S" marked. Link to comment Share on other sites More sharing options...
reconbob Posted March 28 Author Report Share Posted March 28 Here is a photo of two sears. The one on top has the correct thick leg which means that the sear will be depressed farther by the sear lever. Bob Link to comment Share on other sites More sharing options...
halftrack Posted March 29 Report Share Posted March 29 The parts with “excessive” material, can they be saved by removing the excess? Link to comment Share on other sites More sharing options...
TD. Posted March 29 Report Share Posted March 29 Bob, Thank you for the picture. It appears the Sear on top made by Stevens Arms (square S) is within proper specification. The problem Sear on bottom was made by Auto-Ordnance Bridgeport. Stevens Arms had been making firearms for many years prior to World War II so I would assume their inspection process was pretty good. Auto-Ordnance Bridgeport was a very short-lived firearms manufacturing operation. Are most/all of the problem/out of spec parts marked "AOC." Or some other WWII contractor other than Savage or Stevens? I also wonder if an AOC Sear and AOC Sear Lever if mated together would work properly. All good stuff!!! Link to comment Share on other sites More sharing options...
reconbob Posted March 30 Author Report Share Posted March 30 The sear with the "excess" material is the good one, because it will be pushed down all the way clear of the bottom of the bolt. The thin one might still stick up into the path of the bolt maybe 1/16" so pulling the trigger will not release the bolt. Of course its the trigger, disconnector, sear lever, and sear working together. As long as pulling the trigger drops the sear all the way and releases the bolt all is well. But if the sear does not drop down far enough to release the bolt when you pull the trigger all the way, some aspect of these parts is wrong. Bob Link to comment Share on other sites More sharing options...
Bridgeport28A1 Posted March 30 Report Share Posted March 30 This thread is going to have me looking at my spare sears and sear levers. The odds of me ever needing any of my trigger frame parts is likely near zero. But they are not making them anymore. Link to comment Share on other sites More sharing options...
68coupe Posted March 30 Report Share Posted March 30 If need be, one could build up the faulty one with TIG weld, heat treated and fitted. Properly done, it wouldn't be very noticeable, if at all. My 2cents, worth just that, on a "correct" gun. I don't think TIG was around in the 40's. I don't know how they would have corrected that, back in the day. They probably had plenty of parts & wouldn't even bother. Karl, 68coupe Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now