I just dip a rag into a can of polyurethane and give the barrel channel a light coat. If there are areas I can't reach with the rag I'll use whatever tool seems appropriate. Cotton swabs work well for tiny areas.

Coyote Hunter - NRA Patriot Life, NRA Whittington Center Life, GOA, DAD - and I VOTE!

No, I'm not a Ruger bigot - just an unabashed fan of their revolvers, M77's and #1's.

A good .30-06 is a 99% solution.