One of my Sons brought me a Mosin 91/30 with ammo, cleaning kit, sling, bayonet, the works. The rifling was great and we shot it and found it accurate and very powerful, would shoot through 3/8th inch steel with the Russian ammo. Which has corrosive primers and necessitates a good cleaning after firing. I have used WWII GI bore cleaner as well as hot soapy water both of which clean and followed with an oily patch, prevent rusting.
There was a negative factor with the rifle and that was the trigger pull. I knew something better was needed and ordered a Hubers Concept trigger for the rifle, cost was pretty high but with installation and adjustment it is super ! I did prepare a couple of shims from the back of a phone book and placed them under the sear to even lessen that some more. Great trigger now !