Take care of your mosins like you would any other 70+ year old rifle.
I know they used to be $90 and still cost less than $400, but they are still a historical firearm and they need a lot of care and oil to stay in good condition.
If you haven't had yours out in a few years, take it out, oil it up some, and head to the range with some new production non-corrosive wolf or tulammo, and have a blast. It may shoot 3 inch groups at 100 yards if you're lucky but few guns bring as much enjoyment per shot.
Just be careful not to fuck up your hand cycling the bolt.