Western book data with a 120tsx is 49.1 @ 3,062fps (24") 57.9kpsi.
My notes with a 120 Nosler BT, 2.800, WLRM, nolser brass, 22" barrel, 45F.
BigGame mean fps max-min group
48.0 2,928 23 3/8"
48.5 2,948 17 1"
49.0 2,977 8 5/8"
49.5 3,015 15 3/4"
49.5 seems like a sensible max with 120BT; 25fps / inch of barrel difference is a perfect match with Western's max velocity. Although I would probably pick 49.0 as a hunting load; sufficient velocity and accuracy, and single digit velocity spreads with a ball powder is pretty impressive.
I would seat that 120 PH deep enough for one caliber of neck tension (probably around 2.730 IIRC) and shoot from 48.0 to 50.0. Nosler lists 52.0 as max with 120s, but that does not correlate with Ramshot's data - I tend to have more faith in the powder company's data than Noslers (laughably fast velocities in many cartridges).
PS. if you have a new lot of BigGame, may want to start lower to verify lot burn rate.
