From Cartridges of the World, 1969

Bullet diameter .458
Neck diameter .485
Shoulder diameter .530
Base diameter .577
Rim diameter .660
Case length 2.75
Cartridge length 3.25
Berdan primer .251
Knyoch primer 31A

Black powder load
310 grain cast lead
120 grain FFG
mv 1800 100yds 1510
me 2240 100yds 1570

Nitro Load
365 grain Copper Tube
52 grains Cordite
mv 2100 100yds 1809
me 3578 100yds 2655

Pete