I don't think the BLK uses enough powder, with enough pressure, to ever wear out - unless you go FA - and I'm not sure that would burn out a barrel. All three of my uppers (a BHW, a S&W, and an AR Stoner) just seem to get more accurate the more I shoot them. IIRC, round could is about 1500 on all three.

I have a number of PSA products. I consider all of them to have been a "good buy". You might want to "bed" the barrel because some of the uppers seem to be a bit on the loose side, but that all depends on your specific assembly.