Now for the other project I've been working on, the M4 barrel by AR Stoner, $70 on sale IIRC. This thing is horrid, linear scars across the lands, huge swell at the grenade launcher wasp waist, tight spot behind the gas block, pits, scars, and a throat so tight that 5.56 primers fall out in the action. It's clearly marked "5.56 NATO" which is pure balderdash.
Anyway, I shot a series of soft lead, 320-grit impregnated bullets through it with a pinch of Titegroup, about 20 rounds. Then I ran some more 5.56 through it to see if the throat moved enough to not blow out the primer pockets, but no improvement there and it coppered to buggary. A week of cleaning and here's where I am, still like an anaconda full of baboons but somewhat better. This is why soft lead is the thing to use for uniforming barrels for shooting cast bullets, this shot near the throat:
Farther down, the tight spot just before the gas block, note how almost the whole surface has been cut by the laps:
Farther down we have more normal bore size (same as the first and last few inches) and then this bulge at the wasp-waist in the profile, note how it has barely been touched by the laps:
Pretty neat, huh? I mean aside from the obviously horrid bore. If I didn't have a $50 suppressor-mount brake pinned and welded to it and a $130 JP adjustable front sight gas block captured on it I would just trash the thing and buy a better one, but I might be able to save it. Maybe. It shot 10 into 8" at 100 with ball ammo after this round of lapping....