Thanks for the tip, I could imagine how comso would get in the way if not properly removed.

I actually have a lot of experience with C & R rifles (have a 03 FFL). Whenever you get a C & R rifle, it is best to break it down to its parts and soak the metal ones in boiling water with a good amount of Dawn detergent in it. That will remove the cosmo. My Mosin went through the process and has no cosmo left in it.

I suspect it is the surplus ammo I am using (it has painted casings). One of these days I may buy some new production ammo and try it out.