I have an Indianapolis Ordnance Sten Mk. V conversion and several friends have IO conversions for the Mks. II and III. We all have the same problem, which I hope has been addressed and solved (have already checked this site and with IO who, while very polite, state this is "abnormal").

The IO conversion uses two small-diameter springs, one for recoil and one for the firing pin striker. They give suggested starting lengths for each, noting each gun will require adjustment.

The problem each of us faces is that with the recommended spring starting lengths, and even cut shorter in 1 coil increments, the IO bolt is literally impossible to pull back (the Hulk excepted, I suppose). When the springs get too short, either the bolt will no longer fully close or the firing pin does not receive enough energy from the hammer to fire the cartridge.

Between us, we've gone through about a dozen springs with no resolution.

Has anybody experienced this, and has anybody successfully resolved the issue?

TIA.
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