My wildcat has a case capacity of 108 grains of water, compared to 136 for the .450 NE. After all, the .450 NE was a black powder case originally, and had much more capacity than necessary for modern double base smokeless powders. I believe even the cordite load required a fiber wad to fill up the void in the case between propellant and bullet. I could duplicate .450 NE velocity with 79 grains of Norma N203, if I remember correctly, which gave low pressure and good loading density.

The .375 Flanged brass was easier to obtain in those days, and I had negotiated with Winchester to do a run of flanged cases, which they could do with existing machinery, obviously not the case with the .450 NE. The .375 Flanged case offered all I needed in the way of case capacity, since my aim was to replicate .450 NE performance in a more modern rimmed case, at pressures appropriate for a double rifle or single shot rifle action strength and extracting capability.