My son brought me his Rem 700 ADL. The scope was junk to start with and he bought a new Vortex scope. I started from scratch with the mounts on up. Cleaned the barrel and bore sighted it. I built a set of ladder loads with both Varget and H380 using 55grn Horn V-Max. I loaded them .010 off the lands. Hand primed used brass. All brass was checked for length and was well below trim length.

Took to range. I was able to shoot the H380 loads and kept them under 1-1/2" 5 shot groups. All groups shot 7 o'clock 2 inches out of POA. He wanted the rifle back to shoot 'yotes with. I loaded up 70rnds of the best shooting load and went back to set the POI. It looked like I closed my eyes and just slung lead!!!!!!!!!! Even with just minute adjustments of the scope, it would make 4-6" impact difference!!!!
I about fell off the bench. I have been the only one to handle the weapon. It was always in a hard case while transported. Not dropped. I used cleaned, trimmed, loaded the same powder charge from same jug. Same batch of projectiles. I thought I may have mixed up the load data results. I loaded up 2 different loads, 36.0 grns and 38.0grns and loaded with what I thought was the same primer and went back to range. Same results. I can barely keep them on a sheet of paper now. Any ideas? Could changing just the primer make that huge of difference? I also loaded the experimental batch with remington brass thinking that that may have been the issue. Nope.