Few thoughts. First, do you know whether the rifle ever shot well? An inaccurate .222 would be an oddity but.....
Second, I love Powerl-lokts. You can drive them fast. But they have never shot well for me in a high-mileage or rough barrel. Not one of my gas-ported M16 uppers - and I have a bunch, 1:7 to 1:12 - shoots them well. Whether new or a 20k+ blaster.
Third, do Kroil/paste benchrest cleaning technique. Use a borescope if possible. Did that to an 11.5" at around 18k. It was doing about 6-7" at 100 following ammonia-based cleaning. Yup, just like an AK. Borescope pics were ugly, lumpy deposits, carbon ring, plus some non-fixable ugliness. After the aggressive clean lumps and ring were gone. It then shot five of my best M855 into 2.5", which is about as well as the others can do. Accuracy deteriorated quickly until aggressively cleaned again.
