Got a mosin in yesterday. Guy hadn't cleaned it real well since the last range trip about 2 months ago. Got a hold of it and there was surface rust inside the chamber and the barrel. Guys the surplus ammo is EXTREMELY potent and WILL cause corrosion. Running a few patches through with Hoppes isn't going to do anything... You need to run a brush through, then soak the barrel in Hoppes and then start running your patches. Hoppess and most gun cleaning solvents are designed so they eat away at the GPR and salts and whatever else might be lurking in there. Spend some time with your guns, or you may just end up ruining them. These surplus rifles, hell any gun, NEED attention and to be cleaned PROPERLY. Also a good tip when you are done running your patches is to soak a CLEAN patch with gun oil and put it on in there. This creates a pretty nice barrier to prevent rusting (to an certain extreme) and overall keep the gun in nice working condition!