hoppdoc, one could make any wildcat that came to mind, but then it wouldn't be a 450/400NE 3" ! This cartridge has a following, and that is the only way these things would sell well. If one looks at the 500/416NE K it is easy to se, not many folks have bought them compared to old origenal chamberings. This doesn't mean the 500/416NE is a bad cartridge, it isn't, but that the people who buy, and hunt with double rifles are a nostalgic group, that tends to avoid unusual chamberings in double rifles.

The 450/400NE 3", and the 450/400 3 1/4" have always had a thing with the .408, and .411 diameters, and it is a common practice to slug any barrel on either of these two chamberings before loading. By makeing all new ones .411, there would be no liability matter to worry about. There no danger involved in fireing a .408 bullet in a .411 bore, but the reverse can cause a problem, hence no legal worry for the maker if he uses a .411 bore barrel.