just so you know, a case with a similar size of base would work, so that would be any cartridge based off of 30-06 or .308/7.62 NATO/7.62x51..... that might be....
.270
.308
.30-06
.22-250
.243
7.62.39.... anyhow, I'd be trying these if there's difficulty finding a piece of 30-06.
I think the idea using a 30-06 case instead of .308 is the added leverage the longer case will give you. Other thoughts out there?