Sorry, new guy on the block but seems no one touched on this question or I plain missed it skimming along, so allow me. You've missed a few more common issues, stock bedding and possible crown damage. Not overly familar with your particular rifle brand, I'm more of a Savage kinda guy, but if your stock is warped or pressing on the barrel it can cause erratic accuracy. If it's suppose to be fully floated, try the old school method of passing a single wrapped dollar bill down the length to check for any binding. If so, you should remove what's causing the bind, sometimes on a wood stock it's as simple as a bit of a sealant bubble. A simple nick on the muzzle crown can also cause havoc, or damaged lands and grooves at the muzzle. Since you've tried mulitple brands of ammo and a few different scopes, I'd look here next before scraping it out for something new, unless it's your excuse to the missus.