Originally Posted by they
That said... there is a school of thought to replace the entire upper (including b/bc/etc) every 10k rds or so... if you just replace the bbl you can have problems with other components... kindof takes the guesswork out of it.
Every 10k rounds? Ummm... most quality barrels will go 15,000-20,000+ rounds before their groups truly "open up," and that's only bullet stabilization. There's no need whatsoever to replace your entire upper every 10k rounds. I'd love to hear the reasoning behind throwing out the bolt carrier, upper receiver, and railed handguards simply for the purpose of preemptive maintenance.
Also, 10k rounds is $3,000-4,000, not $5,000. With a quality, free-floated stainless upper (BCM, Noveske, Larue) potentially costing ~$1,000 or MORE, that's not a "drop in the bucket" - that's 25% of the cost of the ammo you shot.
To the OP:
There are many threads on this subject and it's a question I once asked myself. Under "normal" use (60 rounds every 15 minutes or so) and good cleaning, a QUALITY barrel should last you ~15,000 rounds, give or take. If you fire at a slower rate than that, then the barrel life increases even more, potentially 20,000-25,000+. Some barrels have lasted 30,000 (BCM, Noveske) to 50,000 (Larue) round counts. Conversely, you can destroy a barrel in 6 magazines (180 rounds) or less doing quick mag dumps (shooting an entire magazine, reloading, and repeating as quickly as possible). It's ALL about the rate of fire, how long it has to cool down before being used again, and how well it's cleaned.