Whats the brownish stuff?

[number1olddog]

I was cleaning my upper from a top name brand company and noticed some brownish rust like stains on the inside of my chamber just past the lugs. Tried a chamber brush and chamber mop and it won't come off. What gives? The upper is about 7 months old with around 150 rounds down the pipe and it was bought new.

[Impact]

assembly grease maybe ?

[Belmont31R]

Get some solvent, take a section out of a USGI cleaning rod, attach USGI chamber brush, chuck in cordless drill on low speed, dip brush in solvent, insert brush into chamber, and go slow for about 10 seconds. Wash out with brake cleaner. Wipe down with oily rag, and be done with it.




As said its likely assembly/preservative grease that dried up, and then was probably baked on by shooting. Always give a new gun/upper a good cleaning before shooting to get all that junk out of there.

[number1olddog]

That's the thing that is getting me. I cleaned the piss out of it like any new gun I buy and I am not sure why I just now noticed it. I tried the cleaning method you suggested and it's still there. Oh well. I am sure it's not rust as it is still new.

[QuietShootr]

What would be the 'top name brand company'?

[R.D.]

I have a 14.5" LMT that has had discoloration in the chamber/lug area that has seen between 5000 and 6000 rounds with no problems. The carbine is almost never white glove clean so I haven't noticed the discoloration latley. I just shot the thing and didn't put too much thougt into it as it was surface discoloration and there was no visible pitting/rust etc..

It came up on 10-8 forums with another LMT a year or two ago. IIRC the op in that thread had no problems other than the discoloration YMMV.

I would contat the maufacturer to see if this is normal or a possible QC problem.

[number1olddog]

This is what the company recently stated.
(It is chromic acid (brown residue) which is used during the phosphate procedure at a very low dosage) Sound right?

[PdxMotoxer]

i would have guessed assembly grease also.

But ya i don't see why it can be a stain from chromic acid.
that would also be the answer why doing solvent, wire bore brush, low speed drill
had zero effect.
Rust would have came off or at least mostly came off, I'd say don't worry
it's just a stain inside the chamber.



:cool: However i did hear there was some bad Brown chromic acid going around. :cool:
Stay away from the bad brown chromic acid. :D

[number1olddog]

What kind of affect can it have down the road?

[ggt1_02]

This is what the company recently stated.
(It is chromic acid (brown residue) which is used during the phosphate procedure at a very low dosage) Sound right?

It could very well be true, it happens to a lot of the parts my company does. Doesn't affect the coating, its just not pretty.

[YATYAS]

Get some solvent, take a section out of a USGI cleaning rod, attach USGI chamber brush, chuck in cordless drill on low speed, dip brush in solvent, insert brush into chamber, and go slow for about 10 seconds. Wash out with brake cleaner. Wipe down with oily rag, and be done with it.

Thanks, I'm gonna try this! Back in my day in the Corps we used "elbow grease"! I'm going to attatch my drill and START CLEANING! After my next range visit.

[YATYAS]

Get some solvent, take a section out of a USGI cleaning rod, attach USGI chamber brush, chuck in cordless drill on low speed, dip brush in solvent, insert brush into chamber, and go slow for about 10 seconds. Wash out with brake cleaner. Wipe down with oily rag, and be done with it.

Thanks, I'm gonna try this! Back in my day in the Corps we used "elbow grease"! I'm going to attatch my drill and START CLEANING! After my next range visit.

[Belmont31R]

Thanks, I'm gonna try this! Back in my day in the Corps we used "elbow grease"! I'm going to attatch my drill and START CLEANING! After my next range visit.




FWIW you can also take a well used USGI chamber brush, and do the same thing to the inside of the bolt carrier. It will get the baked on carbon off pretty well.




Granted its not necessary to spotlessly clean an AR every time.... its quick, and does as good of job as is possible. I remember the days of spending 2hrs cleaning one gun only to still have tons of crud still come up with a clean q-tip during inspection time. Now I let a drill, solvent, and brake cleaner do the work for me. Its easy to clean an AR to 95% in 15 minutes if you do it right. I use SLIP Carbon Cutter as my cleaner, and then wash everything out with non chlorinated brake cleaner. Just make sure to wipe everything down with an oily rag as brake cleaner will strip everything off including whatever lube was present before. Also use outdoors, avoid prolonged skin contact, and wear glasses. Easy to get splash back in the eyes.....:)

[YATYAS]

FWIW you can also take a well used USGI chamber brush, and do the same thing to the inside of the bolt carrier. It will get the baked on carbon off pretty well.

Thank you again sir.

[Littlelebowski]

Just spray the whole thing out (outside or in a well ventilated area) with non-chlorinated brake cleaner. Don't worry about the carbon that doesn't come off. It doesn't hurt anything.