Here are two good lists I used, just got my gun built. The only one ive tested was the 180gr with 16.3C g of imr 4198 and it shot very well with a 1/8 twist and out of a 10.5in barrel.
http://sierrabullets.files.wordpress.com/2013/07/300-aac-blackout.pdf...
Tried out my new .300blk this weekend, loaded up some rounds with components that I had lying around. Used 180g SBT Sierra Gameking with some 16.3C g of H4198. Seemed a little underpowered, would cycle fine but fail to lock open on last shot. Seemed accurate enough though. Covered my 5 shot...
I got mine at the CMP, I just drove to the store up in Ohio and picked out my own, it was a fun trip and really awesome to see all those Garands in one spot. They are by far the cheapest, you could probably expect to pay not quite double the price from a gun shop.
I dont see them going with the Beretta 96 .40, they are looking to move away from beretta, if they actually adopt a new pistol. They want more ergonomic and more reliability. Berretta offered to fix what the army wanted fixed with there berettas but the army declined. But i've got a feeling that...