It involves smoothing or polishing the barrel by firing abrasive coated bullets through it. You can buy abrasives designed for coating bullets. David Tubb also sells kits of 50 bullets coated in 5 series of progressively finer abrasives (sets of 10). These are available from Cabela's, Midway, and from Tubb's website. I think he makes loaded ammo now in addition to just selling bullets. I've brought the topic up on this website in the past and gotten no positive feedback.
Nevertheless, I tried Tubb's system on my .308 Win. I can't say whether it improved accuracy or not, as I did this when the rifle and barrel were new. What I can say is that it takes fewer patches to clean than my other barrels; and, I see less copper fouling in it.
If you have an expensive, after-market barrel that's been hand-lapped, I doubt there's an advantage to using it. It's made mostly for cheaper, factory barrels. I won't recommend it or argue against it.
