I worked some loads for my Model Seven 300 SAUM (22" barrel) in March using some blem 150 gr. Nosler E-Tips and Superformance. I interpolated data from the 300 WSM, which has listed data w/ Superformance. Using REM brass & Fed215 primers, I went as high as 72.5 gr., reaching 3286 fps but had a little too much bolt stiff lift & primer flattening (the temp was ~75-80*F). I backed off 1.5 gr. to 71.0 gr. @ 3213 fps. My COAL was 2.800" (max for the magazine) which still gives me a 0.110" jump in this long leade chamber (factory). I shot this on a recent cooler day (upper 40's) and got 3156 fps from a cold barrel & ammo. Superformance seems to give the highest velocities with the midrange bullets weights compared to other powders for this cartridge, so I'm happy with it. And Hornady says that it is reasonably temperature stable. Not having any luck w/ the E-Tips accuracy wise though; 2-2.5+" three shot groups @ 100 yd. as good as it gets. I plan on switching to Barnes TTSX in the 130 & 150 gr. when I can find them! I haven't found this Model 7 (or another in 260Rem) to be capable of MOA accuracy; rather 1.5-2+" three shot groups @ 100 yd.
I've also used the Barnes 175 gr. LRX w/ 61.0 gr. of Reloader 17, Fed 215, COAL 2.80", reaching ~2964 fps. & ~1.75" 3 shot 100 yd. groups.
Hope this helps! -Mark & Belle
