I test fired a load of W748 and found unburned kernels in the bore. The load was 20gr under a 167gr boolit with Dacron filler. The penetration and the 'recoil' if one can call it that would indicate reasonable velocity. Recoil was a push and the muzzle blast was greater than the same load in H4227.
I could increase the charge until I get complete combustion but I'm wanting a gentle launch, rightly or wrongly.