I was lucky enough to score some old Du Pont, IMR., SR 4759 recently.
I hadn't heard of it before a friend offered it to me, and gee I'm glad he did.
For those that don't know it, it was developed as a specific reduced load powder, but apparently went out of production.
I like a bit of reduced load playing around, but was having trouble getting Trail boss to work in my Jungle Carbine.
No probs now, and the groups tightened up with the 30.06 and 6.5 on cast loads.
Not sure if it's back in production, but it's definately worth a look.