In my experience, rifles are more picky about the bullet used than the powder used, generally speaking of course.
If you really want to use this bullet, you could try a couple different charge weights with said powder and bullet, and maybe even a couple diffferent seating depths with same, but if that doesn't show any promise.....perhaps the gun just doesn't like that particular bullet.? Especially if it's a known accurate rifle that's proven itself before with other bullets.
4831SC should be a fine powder to use in 270, it always done me well in 25-06 with heavy bullets and 6mm rem. and 243AI too for that matter. Alot of folks say it's good in 300 WSM
as well, I don't know of any reason why it wouldn't work well in a 270.