A friend of mine has two .264's. One is a factory Rem 700, the other id a custom build. He sent this data for comparison to my 6.5-06 AI.
All loads are with 142 gr Sierra MK's
Loads I've worked up to in the Remington 700 .264 win mag with 24 in barrel.
H-4831SC 60 gr 2856 fps 32.0 Sd
VV N-560 60gr 2869 fps 6.0 Sd
VV N-165 58gr 2804 fps 21.3 Sd
IMR 7828 58gr 2844 fps 17.5 Sd*
Rel-25 63gr 2912 fps 5.3 Sd
VV N-170 65gr 2890 fps 30.4 Sd*
Magpro 62gr 2860 fps 69.0 Sd*
H-1000 64 gr 2924 fps 24.7 Sd*
Magnum 66gr 2879 fps 42.0 Sd
Retumbo 63gr 2824 fps 24.0 Sd
VV N-570 66gr 2919fps 23.0 Sd*
H US-869 76gr 3024fps 29.0 Sd
The 30 inch barrel gives another 100 to 200 fps over these loads.
Loads marked with * are not showing signs of pressure on primers yet and so will be increased a grain at a time until pressure signs appear.
The ones not marked with * are likely to be less than a grain or 2 away from max
It seems Sd varies quite a bit between guns so, to an extent, what is good in one may or may not be good in the other. I haven't tried many of these yet in the 30 in barrel..
I think both rifles have 1-8 twist.
Disclaimer: "Start low and work up"