Fire lapping a 303?

[RJW NZ]

The funniest story in the book is a police dept who bought a series of pre embedded loaded cartridges for a Galil; All four grits, 10 shots each, and 20 shots of 1200 grit', and as quick as you could cycle the gun and change 5 mags the job was done!
After a few warnings about that and the value of taking more time the comments are about a .308 that opened up from .3075 to .3095 (20 thou!) and get this, the groups went from 3 inches to 3/4".
There's other stories about rolling bullets in valve grinding paste to do the job, ... easiest way to end up with a shotgun I'd think.

Those pics of Eds with the chattering marks are basically shocking, no wonder the copper hooks into the barrel.

Are there custom barrel makers who set out to make barrels that don't have chattering marks, seems there'd be quite a market, or do we have technology limitations?