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 (http://www.apachegunworks.com) and made famous around here by Dean (scope eye) our resident speed/cannon freak.