Suppressed R15 Dirty Brass

[jbeltz7]

Shooting my Gemtech equiped Bushmaster yesterday for the first time I was using brand new 55 grain FMJ Remington/Federal ammo and after being fired the brass was filthy. I have never seen once-fired brass so covered with black powder residue, the outside of the cartridge case was almost the same color as the inside. Is the extra gas blow-back is causing the issue or is this common for the AR or do I possibly have a problem with this rifle? TIA

 

[Jason_G]

Is the extra gas blow-back is causing the issue or is this common for the AR

Don't own an AR or a suppressor, but I'd say it's normal, and a product of DI. That crap's got to go somewhere. Someone please feel free to correct me if I'm wrong.

Jason

 

[W.E.G.]

Normal with my Gemtech/AR

Face full of gas too.

I'll venture the gee-whiz piston-driven AR's filthy the brass too.
95% of the crap coming back in a suppressor gun is coming down the bore - not through the gas tube.

 

[Jason_G]

95% of the crap coming back in a suppressor gun is coming down the bore - not through the gas tube.

Yeah, I guess you're right. I guess the only reason I noticed it with ARs and not with other rifles is because, like you said, it's coming back into the shooter's face through the charging handle opening.

 

[JustinJ]

Running a can on my ARs, sig 556 and MSAR causes the same dirty case effect.

Interestingly I have a USC to UMP conversion with a 16" barrel (for the time being) that does the same thing to .45 brass.

 

[Zak Smith]

Fire about 10 rounds, then leave one in the chamber for 10 seconds, then eject it. The unfired cartridge will be filthy from the gas pushed back up the bore.