Editor: You can certainly use a bronze brush without damaging a barrel. But many shooters do brush more than necessary. I would say though, that 10 solid minutes of bronze brushing could well do some harm if you were just stroking back and forth. The reason is that the brush is carrying a slurry of solvent, carbon, and tiny hard particles of primer residue etc. We recommend that you start conservatively, and do the minimal cleaning required to maintain accuracy. If you have a good barrel that shoots great when new, it should be your object to NOT do anything that would change the internal dimensions, surface profiles, land/grove geometry, or crown quality. This is just a variation of “don’t mess with a good thing”.

Cheers Rustij