It sounds like lead build up but could be copper . No mention of bullets usd for the 100 rounds, or velociy of the ammo. KG12 is the best copper cleaner and works on lead and its safe to use. Sweets and a few others. Also plane ole Kroil Oil well lift copper and lead. If its messed up good you may have to fill the barrel and let it set over night dependine what happened. I hate to mention chior boy but a piece of that stuff wrapped around a bronxe brush can strip out what the flacking after it is loosened.
tell us more about the loads you used.
tell us more about the loads you used.
