Developing 260 load

[rmkey]

So far I have obtained groups of 0.65 moa with the following:
Savage LRP 260 rem around 75 rounds fired in gun. I am using MP7 cleaner, copper remover and oil.
142gr SMK
44.0 grains of H4831SC and 40 gr of Ramshot Hunter
Lapua brass new
WLR primer
2.880 COAL jammed

Do you think I should switch primers? I know H4350 is the powder but I haven't be able to find it.
Do you think i should back off the lands 0.02?

Same set up for Berger VLD 140 grain except COAL 2.950 and 44 grains H4831sc jammed got groups of 1.0 moa
Backed up .04 off lands and the group opened up?

All shot taken off bag in prone position. Have not used lead sled.

Just out of curiosity what kind of moa can be expected, shooter disallowed, at 100 yards from this gun?

Loaded 43.0 grains H4831sc and backed OAL down to 2.935 with the VLD and much to my delight got 0.45 moa. Tried some a-max 140s .02 off lands and they were well over 1.0moa.