308 with 180gr Sierra Pro Hunter Round Nose (flat base) and Varget. Working on creating a load for this round using the OCW test at 100yd. I noticed that sometimes my first round would be inches away from the other rounds in the group. This never happened when using 165 game kings, 168 SMKs, 168 MATCH, 175 SMKs, 178 MATCH bullets with H4895 and Varget. After the first test I noticed my suppressor was loose and thought maybe that was the problem. Did another test and made sure it was secure throughout and still had the issue. First test was done prone off bipod and rear bag. Second test was done off bench with bipod and bag. All shot with Magnetospeed V3 attached to the stock so not touching the barrel. Always check the scope base/ring and stock torque specs before and after shooting. Brass, bullets, powder, and primers are all from same lot. Powder weighted from RCBS Chargemaster lite. What could be causing this?
Short Action Customs 308 22" barrel
Trigger Tech 1.5lb trigger
Nomad L with Area 419 mount
Sierra Pro Hunter 180 grain
Alpha munitions brass 5x fired and annealed after each firing