The trigger puller is the most important factor.

What "wears out" a barrel?

Number 1 - improper cleaning
Number 2 - throat erosion

Number 1 can be taken care of by cleaning from the breech out, and use of a coated cleaning rod.

Number 2 - happens every time you pull the trigger, and the higher the round count the more longer range accuracy degrades. A chrome chamber will slow this down, but the throat area is still burning away with each shot. In CMP competition shooting, a "worn out" barrel will no longer group well at 600yds between 5-6000rds. That same barrel will still shoot MOA at 300yds for 2000more rounds, and MOA at 100yds, for another 10,000rds. As a barrel wears, the longer range accuracy drops off. If you don't do much shooting beyond 300yds, it will take a long time to notice any degradation in performance.

The chrome lining in barrels doesn't know if its over CHF barrel, CM-V, or 4140 or any other barrel steel. In regards to rifling, the chrome lining in the bore/lands and grooves doesnt wear out either. You will never end up with a smooth bore from shooting too much. So if you think you are getting any measurable extended life with "thicker chrome", think again.

Just get whatever brand name barrel you want and you cant go wrong. You'll never know the difference between a 4140 RRA barrel and a uber expensive CHF barrel.

How long will an average AR barrel last?

Having a good view of the "average" gun owner, here is how I do the math:

If you are getting 1K rounds for $350, you are probably buying some steel cased crap. Most serious shooters, who shoot a lot/train, don't shoot that crap so figure at least $400 per K.

If you want to be realistic, 99% of ARs sold will never shoot 1K rounds in the owners lifetime, so why "barrel life" comes up so often is another puzzle. I consider myself a high round count, serious shooter and I shoot about 300rds a month. When practicing/training real drills, and marksmenship, 300rds goes a long way.

So lets say I shoot 3600 rounds a year, at a cost of $1440.00, or $120 a month. I'm sure I can get 20K rounds out of my barrels, so I'm replacing my barrel every 5 years at after spending $7200 on ammo.

If my training ammo wasn't a business expense, there is no way I would be able to afford $120 a month out of my living budget for shooting.

Id say the average AR owner shoots 300 rounds a year max, of which 75% of that shooting is done under 100yds. So basically the average AR owner, with 1 AR, will spend a lifetime to "wear out" his barrel.

- Steve