if i were going to try to push them hard i'd probably look at 1680 or shooters world blackout (do63). folks are pushing 150's beyond 2000 FPS with a nicely compressed load of 1680.
hornady just released (as ammo) a blackout load with 135gr FTX. im waiting on the bullets to be sold as components. If you could push those at 2100 fps or so (should be relatively easy, with multiple powders) that should easily give a 150 yd load, maybe a bit further if you could get em into the 2200 range, but that would take some testing.
hornady's factory load is running 2085 FPS.
http://www.hornady.com/store/300-Blackout-135-gr-FTX-Custom/
