I had previously managed to get some old 275 grain Barnes bullets to work, but they have not made those for years.
So I bought some 275 grain KODIAK BONDED BULLETS. They have a flatter point and they do not taper so fast. SO I had to seat them deeper.
At first they were all over the place.... BUT TODAY
350 Remington Mag. Ruger M77MKII Stainless
275 (276.4 actual) grain Kodiak Bonded
56.5 grains RL-15
Remington Virgin Brass
Winchester Large Rifle MAGNUM primer
2.800 COL, No Crimp
Temp 20 F, 15kts wind
MV= 2,450 fps and a 0.75 inch group. super clean brass, moderate pressure
Also tried some WLR standard primers.
MV= 2,400 fps and a 2.0 inch group.