Re: .277 dia. 115 gr HPBT MatchKing
I'd venture that the load stated is ok to start below. I'd think that 4831(sc) would be a bit slow for that bullet.
I got 3600+ out of a Win & 90 & 100 gr bulets w/N204.
If a Win w/130s & 58gr of 4350 was just a bit hot but good enough for a standard hunting load it may be a decent powder to try w/the 115s in the WSM.
Maybe someone w/that internal ballistics program (forgot the name) could shed some light on your problem????
I may be the slowest guy on the mountain . . . . but . . . . I'm on the mountain!