Try dropping 10 grains and try a full diameter Power Belt. I swab after every shot with BH209 because hunting you are probably to be shooting from a clean barrel.
BH209 requires firm bullet seat.I have used a std volume powder measure and still get groups of better that 3" at 100 yards with my TC Impact. I tried measuring by weight and saw no difference in accuracy.
If using a sabots. I would try a better make.
It is either your bullets or you loading technique. Since it is with both rifles,I suspect the bullets/sabots
