Burnt 9mm brass

[Seven Click's Up]

Yesterday I fired 128 rounds of white box 9mm from my Vector Mini Semi with a 16 1/2" barrel. All the cases were discolored. Black. 1/4" of the way down. And maybe 1/4 of the way around the case. Haven't noticed it before. I always clean the barrel the night or the next night after shooting. I was trying some new mags that I got recently. All was rapid fire, shooting all rounds from the mags. Boy, my finger was getting slower at the end! My full size in .45 doesn't seem to blacken the cases. I bought a long 9mm barrel and had it cut down. I don't think he did anything to the chamber end. It is legal to have a 16" barrel in my state. Any Ideas?

[7.62bthp]

This is typical of blowback weapons from my experiance. Hks, although they have a "locked delay" put a neat stripe pattern from the chamber fluting. The hotter the ammo, or slower the propellant, will cause this. NBD tumble your brass if you're reloading.

The only thing that "helps" is to increase bolt mass (weight) or recoil spring tension. (eg. heavier buffers on AR9mms, a new recoil spring with a heavier compression, etc)

Look for the case bulging at the base end. This would be indicative of a real issue, the carbon is just a pain.

[Noah Zark]

As 7.62bthp mentioned above, that discoloration is typical. It is caused by gas leaking past the case mouth and getting stopped by the rear half of the case that's expanded tight against the chamber wall.

Noah

[blueline541]

I was shooting an HK UMP .45 submachine last week that was doing the same thing. The fired brass was unbelievably black. The reason for the UMP has more to do with the fact that we don't know the last time it was cleaned.

[Fr8 Dawg]

I was shooting an HK UMP .45 submachine last week that was doing the same thing. The fired brass was unbelievably black. The reason for the UMP has more to do with the fact that we don't know the last time it was cleaned.

If it wasn't for sub guns being dirty beasties, chicks and geeks would want to play too!:jester :silly

[Seven Click's Up]

Thanks for the info guys. I don't think it's a problem.

[prebans]

Totally normal.

Mike

[Old Guy]

I tend to avoid Win WB stuff for expensive barrels as a squib ruined a barrel for me. Uzi SMG barrels are cheap but a mini barrel is not.

[jarhead jim]

Like everyone else said.......Fact is, I'm so used to it, I worry if they come out clean!

Jim