ORIGINAL: eldeguello
"I used 4831SC in .5 grain increments."
I assume you worked up in 0.5-grain increments?? From what starting load? How many batches at 0.5-grain increments did you fire? What happened? Did the groups tighten up as you increased the powder weight, or did they open up? Or stay the same? Regular H4831 has always given me pretty good accuracy in the 7mm Mag., but I've never tried the SC stuff.
Yes, 0.5 grain increments from lowest load to highest load (data from Berger). I fired 5 shots in each load. Cleaning and letting cool inbetween. They never really got tight, the best was about 1.5" on three of the shots, then the other 2 would be out another inch or so. The highest load was about a 4" group up in a line. I'm pretty sure it is a OAL issue more then anything else. Once I get some new brass and it quits snowing I'm going to try some other powders and also shoot it single shot with them touching the lands.