Green fouling on end of barrel - question?

[oldguy870]

I just removed my A2 flash hider on my AR15. I am going to replace it with a muzzle brake. When I removed the flash hider, I noticed caked on green material on the crown of the muzzle.

1. Is this copper?
2. Is it best to remove it before I put my brake on?
3. If so, what is the best way to remove it?

Thanks.

 

[MtnCreek]

It’s corroded copper and any copper solvent will get rid of it. Q-tips work good for cleaning brakes and hiders.

 

[68wj]

I just removed my A2 flash hider on my AR15. I am going to replace it with a muzzle brake. When I removed the flash hider, I noticed caked on green material on the crown of the muzzle.

1. Is this copper?
2. Is it best to remove it before I put my brake on?
3. If so, what is the best way to remove it?

Thanks.

1. Yes, oxidized copper that was both deposited there from shooting and from running copper solvent patches.

2. Yes

3. Solvent and a light brushing with a nylon brush. If it is a SS barrel, either avoid ammonia based solvents or ensure the solvent is cleaned off completely when done.

 

[mmitch]

Verdegris!

Mike