I was shooting factory and noted higher velocities than normal on the labradar. The 4th shot I pierced a primer so I took the rifle off the line. I got home and took the barrel off the AI and found a factory round would not drop freely into the chamber. My bore scope confirmed I have a significant carbon build up in a barrel with 354rds. I have been using bore eliminator and an occasional nylon brush, but clearly I need to up up my cleaning regiment.
I try and use my bore scope sparingly but I broke it out to find not only is their carbon in the first 6 or so inches of the barrel, I have a nice carbon ring. Anyways, I ordered some bore eliminator C4 and JB paste and until it arrived, used a gentle cleaning cycle and soaked the barrel overnight in kroil.
The C4, and a kroil soaked patch with some JB took care of the ring and carbon, so a factory round will now drop into the chamber un-impeded.
Pics show the pierced primer and the small piece of the cup that gets blown back into the AIs bolt assembly.