Thompson M1 Recoil Springs

[hyrjon]

I have a Thompson M1, .45ACP, semi-auto rifle that constantly jams (stovepipes spent cartridges on ejection). The slide operates very stiffly, as if there was too much spring pressure. I removed one of the recoil springs and it works fine now. Does anyone think there may be some safety, performance or damage issue related to removing one of the springs?
Thanks

 

[1911Tuner]

Thompson

Howdy hyrjon, and welcome aboard.

The answer to your question is...it depends. If the rifle is straight blowback in operation...possibly. If it's a locked-breech design, probably not.

When hand-cycling the bolt...does the bolt rotate or move in any direction other than a straight line? If it moves in a straight line, it's probably blowback, and reducing the spring's force could allow the breech to open too early. Check for bulged cases just forward of the web area. If you don't have any of that, it's probably okay.

Not familiar with your gun, and I think we can rule out recoil operation...but watch to see if the barrel moves while you hand-cycle the bolt. If it does...it's a locked breech/recoil operated design, and reducing the spring
won't likely cause any safety concerns.

 

[Jim Watson]

Tuner, hyrjon,

These semi-auto Thompsons are straight blowback, even the ones made to look like a Blish system 1928.

They are so heavily built that I don't think there is much risk running it on one spring, but the off-center load might have some bad effect in the long run. I think you would be better off to get some extra springs and start clipping coils from both sides to reduce the resistance with frequent test firing to keep from cutting off too much.

 

[Spartacus451]

Hotter ammo?

Could one solution be to use hotter ammo? I imagine it is intended to fire something a bit peppier then WWB.

 

[rodinal220]

Without examining your tommy and your ammo it could be a host of things.I have several of the semi-auto tommys all West Hurley guns(WH) before Kahr Arms bought them from Gun Parts Corp/Numrich.I haven't had any issues with mine and have been 100% with 230gr ball ammo.While the WH guns have a spotty QC record the Kahr Arms guns are even more so.If your M1 semi is a Kahr send it back to them.Here two companies that work on both full auto and semi Thompsons.

http://www.tommygunner.com/


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