Based on what I'm hearing and what you've done so far, I would start with your scope. I have had a similar situation twice, and both times it was the scope. Crosshairs we're messed up in one scenario and I remounted the scope in the second scenario. The first scenario I mounted a second scope and it shot normal so I sent the scope in to Leupold and they told me there was an issue with the cross hairs. When I got the scope back from Leupold, the problem was fixed. I was shooting 3-5 inch groups before it went in to Leupold; then back to sub MOA afterward like it did originally. In the second scenario, I never narrowed it down to exactly what was wrong but after remounting the scope, the gun returned to shooting well so I assume something was loose. These were two different rifles about 10 years apart but both went from shooting sub MOA to unpredictable shot patterns; both were related to the scope and or how it was mounted. Good luck.