Are you having trouble shooting this rifle?
There are things that can be done if you're having trouble.
Heck, none of mine have liners at all. One has a simple drilled hole, the other is outside coned, both light fine.
Cold blue if your talking the Birchwood Casey stuff and simular, would look like Crappola on a longrifle unless you're doing something special like a French Gray. See the pewter thread. Out of the bottle, a cold blue on that rifle, would be like wearing a tux with a greasy T shirt.
If you want blue, research and do a Rust Blue or Charcoal Blue.
Do it right.