What happened to the crown of my barrel wtf?

[Blaw]

I just swapped out my brake...and noticed the crown of my barrel...wtf is going on here?

Its a tikka stainless 6.5 creed
It has a stainless adapter for 5/24.
Brake was bored for a 30cal. Never had strikes or anything.

 

[flyfisher117]

Kinda looks like caked on carbon.

 

[Blaw]

i went at it with steel wool....it looks polished now....the crown looks melted.....is that a thing?

 

[Mag_7s]

I only see carbon as well. It's normal to have a little carbon build up behind the brake. I wouldn't use anything abrasive to try to remove, just thread your brake back on and it will be perfectly fine.