Hodgdon's reloading data shows a trim length of 1.275, so max. case length should be 1.285. COL is 1.640. Since it's basically a shortened and necked up .45-70 case, case diameter should be .505" with a .608" rim, .070" thick.
Don't have my Hodgdon manual with me, but it is basically the new-style .475 case cut back to 1.285". They had to cut the original 45/70 rim dia. down to allow the .475 to fit in the FA gun; with the smaller rim dia. you can get six in the Super Redhawk cylinder, with the rims literally touching each other.
As far as overall length goes, the Ruger cylinder, being of .454 Casull length, gives you a lot of room to work with. I think you could run nose-to-crimp (NTC) length all the way out to .5" and it would fly. Be a project for a custom mould maker if someone wanted to tackle that.
I just found the correct dimensions. Rim diameter is .542", quite a bit smaller as Mike thought; thickness is .070". Case diameter is .504", not .505". Bullet diameter is .475", same as the .475 Linebaugh. Case lengths is correct at 1.285" and COL is 1.650", not Hodgdon's bullet specific 1.640". They're in the May 2001 Shooting Times, page 44.
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