If the pits are not too deep, they may can be sanded out. When bondo is put on a car, it is filed, then sanded. Sometimes when the primer is put on and it dries, there can be small pits appear. They make a Laquar based product that comes in a tube like toothpaste; it is a GLAZE and can fill small pits in which all rust has been removed. You can also use JB WELD as a glaze. Put it on with plastic paddle or putty knife.These will work, I have a rifle that the barrel was in severe condition on the outside but the rifling was good. The rust has to be removed and stopped in the bottom of the pit for a glaze to work and hold up. Every layer has to be oil and rust free. There is usually more than one way to skin a cat.
I got to thinking about it today, I need to clarify that I put a Matte Ruger Brownells Epoxy for a finish coat and it has held up well, I forgot and left the little rifle in a case inside the tool box of my Ranger for a month or too. I am thinking Duracote would do the same thing but it would not work with blueing.