Re: Powder for DI VS Powder for Piston 308
Looks like somebody has been drinking the cool-aid.
By far the broadest .mil deployment of these types of rifles is a gas impingement model. Another branch of the .mil tried a piston rifle as their semiautomatic sniper rifle, recently dumped it, and has now ordered the same gas impingement rifle as the other guys.
Both branches have standardized on M118LR for this weapons system. If you really want to know more on the subject, do some searches and read up on M118LR specifications and testing before picking your gas gun load. Also understand that the powder they use may or may not be available in a commercial equivalent, depending on their ((Lake City Arsenal/ATK) latest powder buy and from whom.