What is a 500 Cyrus? Saw it in new Hodgdon reloading manual. Case is from Dakota and the trim length is the same as an 8x57 but it holds more powder than a 458 Win so it must be one fat case. Max load was a 500 grain at 2250 fps with 81.5 grains of Benchmark. Just never seen this on the AR before. Of course I don't see one in my future as I do not need something that big.

That's a new one to me

Here's a link that explains the 500 Cyrus.

http://www.crossoutdoors.com/cartridges.html

Funky cartridge slightly better than the 500S&W.-Rob

uses .500 bullets, and light/low sd at that..

but, would be cool in a wsm based 16.5" rifle...

but, well, i'll keep doing what i am doing