How number of rounds can I expect a AR barrel to last?
I have the 2001 AR15.com (RRA Carbine) with a Wilson chromo barrel that has fired almost 10,000 rounds.  Most of that was just plinking but some of it was extended rapid fire and bump-firing.  Recently I noticed the accuracy of the rifle went from about 3-4" to 5-6" at 200 yards in last several hundred rounds.  Cleaning didn't help.

Is this barrel "shot out"?
 

"Q: How long will my barrel last?

   A: (with data from Bushmaster and LTC Santose)

   The U.S. Army recently (Oct 2000) reported the Mean-Time-Between-Failures (MTBF) for M16A2/M4/M4A1 barrels is 9600 rounds.  These are chrome lined barrels with a 1:7 twist made out of 4150 steel (just like Bushmaster & Colt use), and they see full-auto use.  Also note the military is using full power M193 & M855 rounds, while most commercial .223 runs 100 to 200 fps slower (with the same bullet weight). The 1:7 twist barrels do burn out quicker than the 1:9, especially under full auto stresses.  For a chrome lined barrel on a semi-auto only rifle 20,000 rounds (or more) can be expected.  [Warning: More civilian barrels are ruined to over (or careless) cleaning than to being "shot out".]  Stainless barrels won't last as long, 4140 steel barrels wear longer than stainless; but not as long as the Colt 4150 barrels (w/o the chrome lined bores). nor as long as the chrome lined bores (given the same shooting)."

your bbl is probably not shot out yet, but its getting there...

The rejection standard for M16A2 is 7.2" center to center at 100 yards.  Acceptance is 4.5" at 100 yards. That is with M193 ammo.

In my testing of three barrels, that I eventually "shot out", it was about 12,500 rounds.

Tony

This is Wilson chromoly barrel without chrome lining.
I usually shoot surplus ammo (a lot of South African and Guatamala stuff) and Q3131A.

You're almost there. Hotter NATO-presure ammo shaves a little life off the barrel...no chrome lining shaves a lot more. Some stainless barrel start to go downhill after as little as 5K.

Just use this upper for your 'bumping'. You won't need accuracy anyway.....

No the three barrels I shot out were not chrome.  All three were from Nesard back in the 80's.  Unfortunately, I rarely put them on paper, but they were all shooting fine at 10,000+ rounds and I did fire some groups with one that was still sub-MOA at that round count.  Somewhere between about 11,000 and 14,000 the bullets began to tumble.  None of the barrels made it over 14k and all seemed good nearing 11,000.

Two of the barrels were 20" .750" and one was 11" .750".  All got hammered with full auto fire and many Beta C mag dumps.

To be safe, I would pull off a barrel once it hits 10k and just use it for a machine gun "shooter".