I ruined a bore with that stuff. I still have the kit if you want it. The bore was already rough as a cob. JB's or nothing would take it out. Firelapped it and viewed with borescope before and after and it rounded off the rifling. Groups went from ~1.1MOA to 2MOA. Tried several combos of ammo and couldn't get my groups back, so I had it rebarreled. I wouldn't do it.