Here is couple of pics of my 14.5" 1/9" Bushmaster barrel. Lots of shooting, not so much of cleaning
Actually this barrel has 10K through when pics were taken...
Shooting distance in all pics is 150m / 164 yds. Diameter of X ring in those target is 2" and 10 ring is 4".
10 shot group of 77gr SMK
desperate cleaning session10 shot group of 69gr SMK
after cleaning.
10 shot group of 77gr SMK
after cleaning.
Barrel throat / case neck area of chamber. Note chipped hard chrome plating.
Rifling in throat area.
Muzzle.
This barrel still shoots 2- 3 MOA groups to 150 meters without problem.
MN
ETA: question for bigbore, do you happen to know source for the throat erosion gauge? Barrel pictured above is wasted but I´d keep track on my other AR barrels, how soon throat erosion starts to exist.