Started cleaning out my 1953 7.62x54 Mosin Nagant last night after using a bore light and seeing a flat copper looking build up in the rifling. I figured i did a good job at cleaning it when i first got it, however, after running a soaking wet patch of pro shot copper solvent IV and letting it sit for a few hours, i pulled out a neon blue patch!

Ive used the bore brush a few times already and while the fouling has been removed greatly, theres still thick build up of copper in areas near the muzzle.

What do you think? Let it sit over night with the solvent in the bore and hit it with a brush in the morning?

I aint ever seen a neon blue patch before!