Changing rear bags isn't going to "shift" POI. If it does, you have major problems..
Agree, the major problem is my hold changed, from sand bag to squeezable bag. Major problem with my technique and bipod.
Well, shooting technique and consistency needs to be had in order for accuracy testing. As for your loads. Based on the information you have given, the one that stands out the most in my mind, I'd try the 66.5gr charge weight and find your lands. If you are shooting partitions, be off the lands by .020". I have a hard time believing your OAL stated at 3.270" is optimum. Like I said in an earlier post, Nosler suggests 3.290" OAL based on SAAMI spec chambers. Unless yours is cut short for some weird reason, you should be well off the lands at your stated OAL. Finding the lands is one of the simplest things to do and one of the first things that needs to be learned when taking up handloading. There are and have been techniques written in load manuals for years on the subject. It seems everyone thinks they need fancy gadgets and tools to determine where the lands are. This is simply not true. Based on your targets, your rifle is a shooter. At this point, I'd be more focused on shooting some 5 and 10 shot groups at the charge weight I suggested, with the appropriate OAL and see what your group dispersion looks like. You'll know right away if its double grouping. If that is the case, shorten your OAL. I suspect you'll be just fine at .020" off though. Also, you said you were going to full length size the brass that did not fit your chamber. I'd suggest learning how to partial full length (PFL) size your 7mm brass. It will produce better/more consistent results and will ensure you have no issues in chambering a round in your rifle.
