Tiggertate...

Were those last vel/pressure readings using US 869? Thanks

Yes, US 869. And remember that Quickload is only a reference and not absolute. Your actual pressures with IMR 4831 may have been lower than that by a good margin.

I bought a minty P-64 "Westerner" some years ago, had it pillared into a Micky G&H stock and started loading for it. I found that RE-22 was too "spikey" for me and slow and tried IMR-7828 and obtained 3350 with 125 NPs and 3250-75 with 140 NPs and sub-moa groups at 300 meters...done!

The 140 NP is good to go for any BC game and I now have a bipod and Zeiss Conquest 4.5x14 on this rifle and even hunt with it once in awhile.

The .264WM is the best of the high-velocity smallbores, IMO and one that is well worth working with to get the results you desire.

I would suggest Retumbo. I have never owned a 264 win mag but Retumbo shined so well in my 300 ultras that I always think of Retumbo whenever someone mentions reloading for an overbore case. Plus the 120 Barnes should do well for anything a lead filled 140 grainer is good for

73.5 grs H 870 and a Sierra Gameking for anything up to and including Elk. Same load and a 120 Sierra for the smaller stuff. cci 250 primer needed. This load has worked for me for over 40yrs.
Aloha, mark

Bohica: do you have a source for H870?