statjunk, sounds like you are just missing your load, what Ill do when Im trying to find my sweet spot loadis; first measure col for that particular bullet, drop it back off the lands .030, next Ill load up three sets of three each of different powder weights in .5 incrementskeeping them all seperate and shoot at three different targets through a chrony, Ill then pick the most consistant load and experiment with COL until Im satisfied or cant get a decent group and change up powders and start over. Proper case prep is a must, not all think it is, but most of them dont do any long range shooting, I start with a clean batch of brass, all the same headstamp, FL size, trim to the same length, de-burr the case mouth,true the primer cup, clean and de-burr the flash hole then run a brush on the inside of the case, finish up by weighing the cases rejecting ones with more than .5gr + or -. All guns are not created equal, you just need to find the right combination for your rifle, when I decided to go to the Barnes TSX bullets, I lucked up with my .300winmag and found a load I was happy with in a day, my AR " was about ready to give up" took me almost four months to find the right combination, both rifles shoot under 1/4 inch on a bench off of bags, I have also gotten that kind of accuracy out of the Nosler Partitions that you have tried, so dont give up on the bullet, just take a little more time to find what your rifle wants. By the way, most bad groups come from a bad crown " the last contact between the bullet and bore", an easy way to check is to ; paint the crown with white-out and shoot three shots and inspect, you should see an even pattern blackend, if not, have your crown re-cut. Good luck!