Welcome to the Forum
Got a chronograph?
(See disclaimer below)
Using R22, load the 190 SMK to about 2900 feet per second.
Shoot that and see how it groups.
Adjust up or down from there seeking best performance at desired long range.
Disclaimers:
A. I don't have any of my manuals open, you'll have to check your own manual for starting and max loads.
B. I shoot that velocity from a 300 Wby Mag, not Win Mag. I'm hoping your cartridge behaves similarly to mine.
[P.S. My Weatherby also gets good long range performance from 175 SMK loaded just above 3100 fps. Factory 180 grain load with Norma powder is right at 3300 fps, it shoots excellent groups up to 300 yards but the soft point square base bullet they use craps out after that. The SMK goes farther. I shoot AMAX in 223 only, not 30 caliber.]