Back when I was doing a lot of competitive shooting, mainly in caliber .308 Winchester, I used to keep close track of the number of rounds fired through each barrel and when the accuracy at 600 yards started to drop off, usually around 2000 rounds, I would have the barrel cut off at the breech end, set back and rechambered. Usually the rechambered barrel shot better than the same barrel did originally. I shot my first clean target at 600 yards with such a rechambered barrel. Starting with an original barrel length of 26", a barrel was usually good for around 4000 rounds and would still keep a group in the "10" ring at 300 yards.

I am convinced that shooting a reasonable number of shots down a barrel, while damaging the throat, actually improves the condition of the rest of the barrel, a sort of lapping process which over time removes most of the irregularities. The average hunting rifle, except for varmint rifles, never gets close to that kind of round count.