I shot the .375 on Sunday. Using the conversion of XX grains of cordite (54) x 1.19 = the weight in grains of Reloader 15. 300 and 270 Woodleighs shot to point of aim and 25 and 50 yards.

So 64 Grains of R 15 regulates well. This is Graeme Wright's load from "Shooting the British Double
Rifle." No recoil at 10 lbs weight, handles well with 26" barrels.
Many thanks to Tinker.