Jeff, I just loaded some 300 WSM for a friend. He has a Weatherby Vanguard with 24" barrel. He shot the load yesterday and was impressed with the results. The three shot group measured .675 at 100 yards. Here are the componets I used;
1. Winchester Brass
2. Powder-62grns H4350
3. Bullet-Nosler 165 Partitian
4. Primer-CCI Magnum primers
5. C.O.L.- 2.820
6. Velocity was right at 2900fps
7.I uniformed the primer pockets, cleaned flash holes, weighed bullets, and checked for runout.
Prior to this load, I tried 64grn of H4350, but the 3 shot group measured more than an inch at 100 yards, not good. However, the above mentioned load with 62grns of H4350 worked great. Good luck!