I made 30 rounds with what looks like will be my 'standard' 260 rem load: Lapua Brass, CCI BR-2 primer, 42.8gr Hodgdon H-4350, Sierra MatchKing 142 @ 2.840" COL.
I had remounted my scope, releveled the reticle and added a Vortex Scope Cant bubble level this week so I needed to rezero the scope. On my first target at 100yds I shot a cold bore shot, 3 scope zeroing shots, and then a 3 shot group to test the zero.
Based on the 3 shot group size, so far it looks like a good load.
Next I shot two 10 shot groups at 300 meters in order to verify 'consistency' of this load across more than a 100yd 3 shot group. The first 10 shot group was great, but the second 10 shot group wasn't nearly as good (mirage started kicking in and the bench started bouncing from other shooters).
It looks like this load will provide the accuracy I need as I continue to learn how to shoot long range (500-1000yd) field/match style.