A longer throat would lower pressure and not create a pressure spike. Look at Weatherby chambers.
I don't know the differences in the chambers of the two, but a lot of the military stuff (5.56) is 69 grain or the SS109 stuff which is a long bullet as compared to most of the civilian stuff which usually is 55 grain and under. Federal makes a gold medal match load with a 69 grain Sierra but I'm not really sure why. We used to use it in all the tactical rifles and snipers but switched to a much more frangible bullet. I think Hornady TAP ammo with a poly tipped bullet.
