Difficult extraction on a Mosin Nagant. Solutions ?

[u/Murray3-Dvideos]

Reluctantly bought a generic *run of mill* 91/30 for an embarrassing price. It has a frosty bore, but otherwise seemed to be in good - great condition with pronounced rifling.

I thoroughly cleaned the gun including the barrel and chamber.

The bolt cycles buttery smooth, chambers and extracts unfired rounds fluidly. But when fired, I gotta halfass slap the bolt up and partially back before the spent casing will properly extract.

To improve extraction, does this sound like something a good chamber polishing would solve ? Or is there some other quirky Mosin remedy I'm unaware of ?

[u/Content_Sky_2676]

If it sticks with both commercial and corrosive ammo, and the brass doesn't show major roughness, then odds are its cosmoline in the locking surfaces.

Remove the barreled action from the stock and strip it right down and hit the area around the receiver ring with a heat gun until it's hot to touch. Watch the cosmoline bubble out. Get a leather glove and work a rag inside the action where the lugs engage to remove as much cosmoline as possible. There's almost always cosmoline back in the locking surfaces where you can't get to it that causes the bolt to bind on firing, and 99% of the time this is what causes mosins to stick.

After you've swabbed it out thoroughly, stick the receiver in a container of acetone or other strong solvent. Make sure the receiver is submerged. Leave it a day and give it another good scrubbing with a rag. Plastic brushes might break down with the acetone so stick to cotton rags. Wipe it off internally and externally and thoroughly re-oil inside and out with a penetrating oil, because it'll be completely dry and prone to rust.

Mosins don't have great primary extraction, so could be other stuff as well, but usually there's cosmoline in the locking recesses as well.