Originally Posted by retyc
I would love to know the answer to that question also....
Well it's a good question so lets talk a little bit about factory barrels.
I have seen very nice, and pretty ugly factory tubes. A bore scope of a new rifle can reviel any gross deficencys in a barrel. I have found the normal reamer marks but also lands completly torn away from what I asume must have been broken tooling, or improper handling at the factory. I also have seen the obvious unconcentric throats and beat up looking crowns. All these things can contribute to poor shooting of a factory barrel. As well as things that are not easily seen such as bore dimensional variences. Break-in may not make a problem barrel shoot any better if there if physical issues with the tube.
Barrel break in is a process that happens regardless of how we treat our barrel. Someone who shoots 100 rounds and then cleans may not be thinking about break in but the process of conditioning is taking place. By doing a shoot and clean we are trying to get the barrel to go into a state of easy cleaning/less fouling quicker than what would occur under normal use. In custom barrels it is much easier because the barrel maker lapped the barrel to a condition that left few to no anomilies in the bore.
So I would say it may be possible for a barrel that fouled from day one, and built up a layer of copper, to be cleaned to barrel steel and "re-broke in" I do not know how effective the results would be but it would not hurt.
One thing I have noticed during my factory rifle days was that most of the guns I had did not shoot there best until they were over 200 rounds fired, and that was after I noticed they started to clean up easier. A Ruger varmit in 22-250 in particular had been a good shooting rifle and I cleaned it about every 20-30 rounds and it always had lots of copper that was a pain to get out. I would guess I was at about 250-300 rounds when all of a sudden it started to clean much easier to the point that I could put over 100 rounds thru her and still have it shooting well. Before that time it had always shot well but not after the fouling built up. My guess is it uniformed and smoothed out to a point that fouling no longer built up as it had. I had not set out to break in this barrel it just happened on it's own.
I just recently had a customer send me 2 used 204 ruger barrels, one a factory savage and the other a shilen. He sent a 20 tactical reamer and wanted the better of the 2 barrels rechmbered/set back. I was thinking well it will be the shilen. Well after the bore scope I picked the savage barrel. It had been shot enough that all the usual tooling/reamer marks present in new savage barrrels were gone and the barrels finish resembled more of a lapped look from the bullets slowly abrading the steel so that the structure of the barrel was parrellel with the lands. The shilen just showed too much erosion for me to feel that it was worth the customers money to mess with. This fellow obviously new how to clean a barrel as no copper was present in either one and the savage barrel did not show any indication of abuse by abrasive paste.
Well the reports were good He was getting groups under .200" and placed 3rd in a local BR match.