to the OP. Seems like you have some mods already to your weapon. Have you considered just cutting your losses on your barrel and replacing it with a quality $300-400 match barrel? From most post I have read and I am sure you have too that a quality match barrel with tight tolerances is a great way to improve accuracy/reliability and repeatability. I understand this post was more for a diagnostic check to see what is wrong, and the barrel may not be the reason, however it seems like you cant go wrong replacing it if it is in your means.