I tried a lot of propellants in my 30-378 but Reloder 25 was the only powder that gave me the velocity of the factory ammo and pressures appeared to be low to moderate.
I also had very consistent velocities and good accuracy with Rx25 too.
I've been using the Nosler 180gr Ballistic Tip bullet but certainly intend to go with a Sierra MatchKings next time I take it hunting due to what I've read here.
I can't wait to get my hands on Hodgdon's new Retumbo Powder but haven't seen any yet.
If it's long it can't be wrong... LDHunter (Long Distance Hunter) from the Piney Woods of NW Florida. I hunt clearcuts for scrawny whitetails... ;)