Removing rust from inside the barrel?

[MP-44]

I did a stupid thing. I shot my Yugo mauser with corrosive ammo and didn't wash the bore out. Now the bore has a light brown coating

What do I do to remove the rust and is there any serious damage?

TIA!

 

[dfariswheel]

First, flush the bore, chamber, and bolt face with hot water to dissolve and flush away the corrosive salts.

The, use some Kroil or bore solvent and a new bronze brush to clean the bore out.
After that, use JB Bore paste to deep clean and remove any remaining rust:
http://www.brownells.com/aspx/NS/st...tle=J-B~+NON-EMBEDDING+BORE+CLEANING+COMPOUND

After that, you'll be able to see the damage.
Rust eats into the steel and makes tiny pits. Once there's a pit, it cannot be removed from a bore, so there will be some damage evident.