When Elmer worked with 4350, only IMR was available. It is not an "EXTREME" powder, like the ADI made 'H' powders.

Hodgdon doesn't make powders themselves. They buy powders or powder companies and sell those products, come relabled and some not. A couple non-relabeled powders they now sell are WW and IMR brand powders, which Hodgdon now owns.

I'd stay away from the faster powders with the heavy 350gr., powders like Re#15 and H4895. In a Reloader powder #19 would be the one and probably increase velocities over all others. It's an amazing powder in some applications.