338fed is another option of a good sub load. Almost every bullet weight in 338fed is worth subbing? 300gr 33cals aren't cheap! However a 358fed wildcat would be cheaper.
Look up subsonic load data on Hodgdon's site. They have a ton of 300 blk loads and 4 308 win loads. I have shot 3 rounds of the 190 gr sub x in a 308 with a 1:10 twist. It seems stable but I am gonna shoot more before I run it through a suppressor.
I would say NO on the 6.5 PRC. To much case volume and to light of a bullet.
