Idaho_Shooter,
I would start with RL33 for the 140.
That seems to be a popular combo with some experienced LR .264 WM shooters.
I just got some Vv N-570, reportedly good for the 26 Nosler/142 LRAB. It's about the burn rate of the old, revered H-870, pretty close to RL-33.
If I was loading for the .264, I'd get some of both and try them. Powder Valley had N-570 last week, haven't checked current availability. It's a coarse stick powder, doesn't work well in a powder measure. I had to remove the powder measure drop tube to keep N-570 from stacking up. I dump a load in my scale pan and adjust the weight.
The Vv 500 series is high energy, nitroglycerine enhanced, lots of power/mass. N-570 is the newest and slowest of that series. Pushing 140's at 3,350 in my 26 Nos., the load isn't compressed; this powder is dense per unit of energy, which should make it ideal for the .264 WM.
DF
