Anybody tried this yet? Looks like it might replace H870.

I haven't tried it, but it appears to be the right burning range for the .264. For a number of years I've used surplus WC-872 in my .264. It is somewhat slower (at least in the lot I have) than H870 and produces outstanding velocities with 140 grain bullets.

Curiously, I didn't see US869 on Hodgdon's website as a tested powder for this caliber.

I checked also. Even sent them an e-gram asking for data on 869 in 264 WM, but I didn't expect a response. Maybe Hogden wants us to use the WW 780 780 is just slightly slower than 4831 so that won't work.
I did try a bottle of Retumbo. It was okay but no replacement for H870. Retumbo is stick powder and my groups opened up. Anybody got a stash of H870 they want to get rid of?

Ramshot magnum would be a good choice.

I have an eight-pound jug of WC852. I was told it was a direct substitute for H380. Was I sold a bill o' goods? I'll do some research on it right now...