Shooting Times .45ACP&.223 Autoloaders magazine just did a 10,000 round report on a Colt Match Target HBAR. They used PMC 55-grain FMJ Target ammo. The test was done over a 2-1/2 day period in this maner: First the weapon was bench fired for group accuracy @ 100-yds.(I will give group details below) Then they fired one thousand rounds in a steady cadence, cleaned the weapon and bench fired again for accuracy. They repeated this procedure for the full 10,000-rd test. The weapon never malfunctioned through the entire test! Although no malfunctions occured, the barrel throat was badly eroded after 9,000-rds. Here is a list of the groups fired from a benchrest after each 1,000-rds.[left]Round ct. 0(zero) accuracy 1.52(inches)[/left][left]1,000 rds=1.48[/left][left]2,000 rds=1.51[/left][left]3,000rds=1.47[/left][left]4,000rds=1.33[/left][left]5,000rds=1.55[/left][left]6,000rds=1.29[/left][left]7,000rds]=1.52[/left][left]8,000rds=0.79[/left][left]*9,000rds=*1.89[/left][left]*10,000rds=*1.21[/left].....*For the 9,000-10,000rd accuracy tests they used Hornady 55-grain SP ammo. This was because the barrel throat erosion caused the PMC ammo to keyhole. I think this is a good example of the AR15's excellent reliability. The normal life of an AR15 was compressed into a 2 1/2 day period without a single malfunction. The barrel was expectedly ruined after the marathon shooting session, but the rest of the weapon was ready for a lot more.

Armalite advises that lowers are good for 100,000 rounds before the fire-control pin holes become oblong enough to be out of spec.  Of course, if you have standard-size parts, you can drill the holes out and use the larger Colt fire control parts.  The rest of the lower should be fine, with normal maintainence of springs and such.

-Troy