Most premium barrels are fairly smooth inside to begin with but as I understand it you are really smoothing out the throat area where the reamer has made minute circular marks. They claim this is where the fouling process begins. I break in every barrel except revolvers with shoot one shot and clean for the first 10 shots then after 3 shots for the next 9. I do this at 25 yards and get my scope on paper at the same time. Does it make them more accurate? Not sure but the extra effort up front makes for much less cleaning effort for life of the barrel in my humble opinion. But again its a personal choice and the success the wvhitman has achieved cannot be argued with.