I have a Marlin 336 that is about 45 years old, it was given to me by my grandfather. When I was in the service, my younger brother cleaned the rifle and then put a piece of cotton in the barrel to keep out the dust, that cotton held Moisture and rusted the inside of the barrel. Now when I shot the rifle, the bullet would keyhole at 100 yards.

Who is a good smith to maybe rebarrel a lever action rifle.

I hunt and this rifle has been sitting in the safe for many yuears, I would like to hunt with it once again.

Give Marlin a call and believe they can fix you up at not a huge price and only problem may be the delivery time. I have dealt with them over the years and had satisfactory service.
Good solid gun that Marlin 336. Deer woods in my area are full of them!!