My Stemple Mk2 Doesn't Run Worth A Hoot

[Jim Morris]

I bought a Stemple Mk2 last fall, and today is the first day that I've been able to take it to the range. I have 5 magazines, all of which appear to be in good condition. The gun failed to fire more than one or two rounds before jamming with a fail to feed.

I don't think that the fail-to-feed problem is caused by the magazines, as it occurred with all 5 magazines. I'm wondering if the ammo (PMC Bronze 115 grain FMJ) could be the problem, or if the gun needs a total rework/tuneup.

[StrangeRanger]

It's not the ammo, PMC is pretty reliable stuff. 

Have you proved out your magazines with a feed lip gauge?

https://brpguns.com/sten-magazine-gauge-good-condition/

Over 3/4 of my mags need adjusted.  Your lot may be better or worse.

You're right though; it's most likely to be a gun related problem.  Make up some dummy rounds (no powder or primer and cycle it slowly by hand and see where it loses control of the cartridge.

[2ndArmored]

Additionally, if you've got a high-speed / slow-motion setting on your phone's camera, you can "fire" a dummy round and record it to see what the weapon is or isn't doing correctly.  Some problems are misleadingly hidden (or appear) when hand cycling but their manifestations are too brief to detect when shooting.

[Rekraps]

Good advice all.