7mm Rem Mag Hornady 139 GMX Load Development
So Im working up a load for my Rem 700 7mm Rem mag with the Hornady 139gr GMX using Hornady cases, Rem 9.5 mag primers, 4831sc. I loaded them up 50 thousandths off the lands starting at 63grs working up in 1 grain increments monitoring velocity and pressure signs. I got pressure signs at 66 grains so I stopped there. I then shot 5 shot groups with 63-64-65 grains. My groups ranged from just over 1" to 2". Velocities were very consistent, so now I guess ill play with seating depth and see if that tightens things up a bit. My question is how much should I vary my seating depth? Ten thousandths, Twenty, Thirty??? Also my average velocity was 2,997 at 63 grains, 3,046 at 64 grains and 3,090 at 65 grains. According to the Hornady manual max is at 65 grains at 3,000 fps and Hodgdon Manual says 68.8 grs at 3,054 fps. Should I use 64 grains as max considering the velocity?
Any help is appreciated!