animalpest wrote:Rimfire barrels are generally softer steel than those used for centrefire. Expect 80-90,000 from the average .22
They might be softer because they're only shooting low-velocity cast bullets - you're not going to wear one out just from shooting it. I've drilled and tapped barrels, cut and filed dovetails for sights, and cut threaded muzzles - I haven't found any centrefire barrels that are especially hard. Possibly with the influx on non-lead bullets barrel life might become an issue, maybe. If you're shooting championship-level Benchrest perhaps you might be looking to replace the barrel at less than 100,000rds, but you can give your "shot out" barrel to somebody who will get several lifetimes of target shooting, hunting and plinking out of it.
I have a barrel that won't group better than about five-inches at 25m, on a very good day, with ammo it really likes. But this is not because it's worn, it's because of the way it was "cleaned" and that it was used for decades for "fishing". Put the muzzle in the creek, wait for fishies to swim near, pull the trigger and grab the stunned fishies. The barrel is 25" long but a cleaning rod only has friction in the first and last couple of inches - the middle is all bulged way over-size. As it had one owner from new in 1940 until I inherited it, I estimate it had well under 5000rds put through it. The cleaning rod is little more than a length of fencing wire.