I had an AA EV2 barrel in one of my BSA's a couple of years ago and when that barrel needed cleaning it started to to shoot high and left, weird! It needed cleaning quite often every 250-300 shots and it always went off in the same manner when it needed doing, so you may have found your answer.
I have also experienced the reg being blamed when it is not at fault, if i have fitted a reg to gun and something goes wrong with the gun later on the owner often jumps to the conclusion that it is the reg, its an occupational hazard!
HFT, for people with only 2 buttucks!
VooDoo TwoTwo The next chapter.