This thread is a fucking travesty. The 105k Hide strikes again...
OP, contact JP, nobody is going to know their rifle better than them. Hopefully you can send it in to either get it repaired if necessary, or a clean bill of health to rule out it being the problem. ANY manufacturer's firearms can have issues, even the top tier. I don't care who made it, any machine can and will break.
Typically, provided you are being consistent with equipment and setup, it's not going to be a marksmanship issue if you are able to produce several good groups on most days, and fall to shit others with only the one rifle. Yes, large frame ARs are a different animal, but this sounds like an equipment issue if he is being consistent otherwise.
My assumptions are these: You know what you're doing on your loads, you're using the same position and equipment each outing, and you are a skilled precision shooter in general.
I would start with a scope other than the PST. Let's face it, they've had issues. Following that, I would use some different factory loads. Get your hands on some from Copper Creek or Southwest, or even step up to premium loads from Cor-Bon, Applied Ballistics, etc. Next I would have other shooters test fire it and you bench rest it to remove you and potential fundamentals issues from the equation. Moving on from there, contact JP for diagnosing a possible issue with the rifle. I would not go tinkering around with it myself voiding the warranty, that's for those of us that build our own rifles.
Everyone else that are participating in the internet tough guy shit needs to sit the fuck down and let the OP have his thread back.