Can Dirty Brass affect reliability in semi-autos?

[LoneStarWings]

Hi,

I've fired about 2000 rounds throuh my M1A scout since I got in 4 months ago, and it has been 100% reliable with one exception.

When I used this ammo, I got a failure to feed or extract every 75-100 rounds:

http://www.palmettostatearmory.com/177.php
http://www.palmettostatearmory.com/images/177a.jpg

The ammo I got is about as dirty as those 4 rounds pictured standing up, and by a good measure the dirtiest brass I've tried to run through the rifle. Every other ammo (and I've used at least a dozen different kinds) ran 100% reliably.

I'm trying to figure out why this ammo wouldn't work well, since supposedly the M1A is designed for M80 ammo, and the only thing i could come up with is the dirty brass cases. Sometimes the bolt would lock back in the middle of a magazine without extracting another round, sometimes the fired brass would still be in the chamber after a shot.

I ran through an entire box of 500 rounds and had 5 of those failures. I've since switched ammo and have fired about 550 more rounds with no problems.

Any ideas?

[azredhawk44]

All I see is annealed case necks... not really dirty.

What is the headstamp of the brass?

Surplus is often surplus for a reason, especially during active war time. It could be undercharged or have moderately contaminated primers that don't set off the powder quite right.

1% isn't too bad though... treat it like a training drill to clear the offending round and get the rifle back into operation.

[LoneStarWings]

The brass was headstamped LC 08, IIRC, I could be wrong about the 08 though. In the batch I got, the whole pieces of brass looked about like the neck in the photos, and they felt greasy/grimey if you ran your finger across them.

I'm trying to figure out if it was a problem with my rifle, a problem with the ammo, or just a problem of the two in combination. It seems odd that this was the only type of ammo I experienced failures with, and in the 500+ rounds since I stopped shooting it, it's back to flawless performance.

It runs Federal XM762D fine, I'm not sure if that's military reject ammo too, as it's slightly dirty as well, but only has about 30% of the grime as the LC marked batch I had problems with.