Nosler, Barnes and Hornady all have 300 WSM data and I use all three. I would wait on the Barnes book though it needs to be updated. The Hornady book cost more but it is good to have because it has more calibers than all the rest.
Here are the loads my Ruger 77 MKII 300 WSM likes:
180gr Barnes XLC
67gr IMR 4350
CCI 250 large rifle magnum prime
.6" group at 100 yards
165gr Barnes XLC
67.6gr IMR 4350
CCI 250
.7" group at 100 yards
150gr Remington Core-lok
69.5gr IMR 4350
CCI 250
.5" group at 100 yards
This is the group in the picture