Remington's target load, that they used with their 40x rifles was, as I recall, 37 grains of 3031 with a 168 grain bullet, they did not say whose. Factory target showed 3-5 shot groups that averaged .43", indoord at 100 yards. I used this load with Hornady 168 grain Match bullets at 600 yards, and was quite surprised. The load shot very well, and there was almost no discernable recoil.
You might also try WC 846 with 168 or 173 grain FA match bullets, if you can find any. I used 41- 42 grain charges in bolt rifles, for 200 and 300 yard stages of NMC course. 748 should work well enough, however I have never used any of it.