JB's Bore Paste will work. Just remember to alternate oil patches will it. After that, a good gun oil on two patches with a brush.

Don't use your old gun oil... it obviously didn't work. Unless you're keeping your rifle in a bathroom or live a block away from an ocean, that gun oil should of protected that bore for years.

Buy Rem-Oil with Teflon or BirchWood-Casey Sheath. I live right-smack in the middle of the Great Lakes where summer days with 80% humidity feels dry. I've left my pistol behind my bedroom bed headboard hanging on a hook for five years without touching it. When I put a rod to the bore a week ago right before a test-fire, the patch came out white as snow. That's how good Rem-Oil & Casey Sheath works.