Seems to be jamming in a National Postal Meter WWII era M1 Carbine, and didn't know if this is a known issue with this .30 Carbine ammo?

USA? Never heard of it myself. If you have not had problems with other ammo then it could be that, some commercial. 30 carbine ammo tends to be under powered.

Post pictures if you can

USA is the older white box stuff made by Winchester.

It’s more likely the gun is the problem.

Or bad mags.

VERY unlikely the gun or the mags......

A USA == armscor ammo, which from some searching has not had the best reputation for reliability.....


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Disagree on 2 points:

A lot of armscor ammo is fine
With an M1 carbine, it’s always reasonable to assume the gun needs new springs or the mag is bad.

Also clean your gas system.  Never had any issues with Winchester white box USA .30 carbine before.  However, none of recent production.

I was a fan of Armscor until recently. I bought 5000 rounds on sale right before the Covid panic ($12 bucks a box of 50) and used it and was pleased overall.

2023 I started buying it as I saw it because it was all I saw in the shelfs and needed .30 carbine. I started having major issues with was I was buying. Hard primers, rounds not seated right in the brass, squib rounds due to not enough powder in the charge.

All my carbines are either Fulton Armory serviced or new ones from there. I personally thing their QC went down and won't buy it now that I can get PPU at AIM Surplus at a better price

Second point is valid. Always replace Carbine springs because one has no idea what the gun went through.

I've sworn off Armscor .30 Carbine and 7.62x51mm 147 gr. Both were hellishly erratic- crap "accuracy", and even a couple hangfires. Didn't even save the brass for reloading. Absolute trash.

Never had issues with it in any of my Carbines and shot the last two boxes I had from the early 90's recently.