I have firelapped a number of rifle and handgun barrels with the NECO kit with good results. I use jacketed bullets as they do not upset like a cast bullet and I think they are less likely to erode the throat. I also skip the coarsest grit unless the bore is extremely rough. Follow the NECO instructions and you should have good results. As your barrel gets older, occassionally fire a 3- to 5-shot group with the 1200 grit. Firelapping is a great tool but it can be overdone.