I would retest now with 2 3rds groups at 43.5, 43.7 or 43.8, 44, 44.2, 44.5.
Look for the tightest flattest group that repeats. You are most definitely shooting at one accuracy node. As you go too high in powder, the orientation will turn vertical and you will get one shot way outside the main cluster. Then all the shots will spread out and you will either run out of case volume or see pressure signs.
Real obvious when you have gone too far.
For a hunting rig with this much case, going to the nth degree of pressure is not in your best interest. consistency and function is far more important - you will be going pretty darn fast already.
Neither is testing and testing and testing - your barrel isn't going to last that long.
So next time out, lets say 43.5 and 43.7gr shoot essentially the same (nice flat or triangular groups around 1/2") with 2 3 rds clusters each load going into 1/2" at 200yds (total of 12rds fired). I would then make up say 10 rds each load and try them at LR.
You are now tuning for lowest vertical dispersion. The group (left/right) isn't going to change but the up and down way out there most certainly will. Real obvious when you start going 400 to 600yds.
One load will drop them onto a target like a spray can on its side - width due to wind but no vertical. When you hold off, that is where the bullet impacts. You aim up, goes up, etc. Each shot goes where you expect it to land even with some wind. Nothing surprising about where the bullet lands.
The load is easy to drive.
The other will be a few on target, one high, one low, one somewhere else, . The shots will land in an unpredictable pattern. You feel like you are chasing your tail and would be better off just holding dead one with your eyes closed. Something 'has' to be wrong with my gear, my scope, my hold, my everything.
1/4 min average, at 200yds is about all your are going to see with this type of set up. you have speed, accuracy, a high BC bullet and enough bullet weight to make a serious impression on your target. Reaching out to a mile is now simply a matter of dialing up when you find a load with no vertical.
Shoot the load over a chrony. Make up a drop table using JBM and use the Litz bullet option. Confirm with your range finder over various ranges. Adjust your drop table to match your scope and rangefinder - you will be close but highly unlikely bang on. Reconfirm next few times out.
You are done and have only fired around 100rds. - go have fun and smoke some poochies.
Jerry
NormB, I wouldn't change the primer and have used the CCI BR2 primers to get match accuracy with magnum cases burning almost twice as much powder. There is plenty of spark for the case volume.
