I was really skeptical about paying a higher price for your lapping tool but I must say that I'm incredibly pleased with the results. First off, I ordered both AR-15/AR-10 tools and they are perfectly engineered and machined hunks of metal. The fit and finish is pristine. Their weight alone should convince anyone these are professional quality tools. I was also unsure of your lapping compound but I used it and was very impressed. It worked quite well. I had my AR-10 lapped in under 20 minutes and that was going slow. If you like to build ARs then the BART kit is a must!