A lot of people don't even run 150 grain bullets in the 3 larger cased .277 caliber cartridges. Unless you are just trying to create a sub-sonic load, bullet weights from 90-130 grains will perform better and likely be more accurate.
Thanks. I have a large supply of .277 150 grain bullets for my 270 Max, but they don't get enough velocity to stabilize in a 10 inch barrel, probably due to the small case capacity.
The heaviest load data I have seen is for 140's (Accurate Powder). Hodgdon only goes up to 115's. Might be able to find loads over at the 68 Forum, but would most likely be homebrews.