Um for 250 gr Speer, I think VV N140 for 2200 fps, 2341 bar?? But that may be for 0.358" bullets. So not sure on 0.366"? I would migrate to VV N140 as it noted as being similar to the old R5(Rottweill 5) which was used in the original cartridges.

Serbus,

Raimey
rse