If you are interested in wildcatting, you should pick up the books "Cartridges of the World," "Designing Custom Cartridges," and "Wildcats Vol I & II." That will give you loads of info on parent cases, dimensions, performance, et cetera.
In a nutshell, there's the 30-06 case (and it's shorter offspring the 308) with a case head of 378" or so, the 284 Winchester with about .505" (same as 9.3x64 and rimmed 45/70), the H&H case with .411" - this is what all the pop mags are made from (264/300/338 Win Mag, 7mm/8mm/416 Rem Mag, Lott and many others), up to the 404 Jefferys with a .452" casehead (this begat the Dakota line, and Remington went about .010" fatter to "invent" the Ultra Mag line), the WSM case at .550" - which is basically a rimless 50-110 from about 120(?) years ago, and then the Rigby with .590" casehead. The Lapua Mag is based on this case, albeit in a bit beefier incarnation. Put a belt on the Rigby case and you have Roy Weatherby's 378, 416 and 460 case.
There are bigger cases, like the 500 Jefferys and 505 Gibbs, but I forget their nominal designations.
Take those half-dozen cases, cut them to .21", 2.5" and 2.8" then neck from .243" up to the point there's no shoulder (e.g. .411"-06 or .458" 404J) and there you have it.
Figure out the bullet you want to shoot, and how fast you want it to go and someone has made at least three cases to do the job.
Hope this helps.
Cheers!
Taylor

.475 for the 404

and there's at least one bore that there is ONLY three cases for... and that bore had to be invented, buttons made, and unique bores made...

.550

jeffe

Yeee-Haaaaaw!

Jeffe, where is Porter? My in-laws are in Ft Worth. I reckon one of these days I'm going to have to come bug you.

For a minute I thought this would be about Tera Patrick

BB,
209 miles south of dallas, let me know when you are coming!
jeffe