500 a square?

[goob]

Useing a 378 weather case. Could you build a large shank action without the barrel nut.

[bootsmcguire]

You could, but with the .580" head diameter you are asking an awful lot of the bolt head and lugs. I would be very skeptical on the idea. I am betting to be safe you would need one of the 338 Lapua Savage actions which use the special bolt head and lugs to handle cases that big.

I could be wrong, but with better suited actions out there for rounds like that I wouldn't risk it.

You might look at the 50 HPDT round (aka the "50 Thumper") that was designed by Jim at www.apachegunworks.com and made famous around here by Dean (scope eye) our resident speed/cannon freak.