The chief pro clean is a useful tool. I think the word "scrap" concerns people and scratched boresimmediatly come to mind. I have seen a barrel cleaned with traditional jag/patch/solvent then followed up with 1 swipe of the chiefs proclean tool. There wasburnt platic resin on the tool that the jag could not get to. Enough seen to convince me that the tool works. Do you need to use this tool between every shot, probably not. Over several shots, likely.

Larry/Harley are correct that this tool keeps the lands sharpwhich is needed to maintain accuracy.Think of these land edgesas aknife edge that requires a stone to resharpen. The nubs on the tool don't actually sharpen the lands itself but keeps them from being rounded off. The tool also gets out the plastic residue that the naked eye cannot see.