Berger's heaviest bullet in 30 cal is the 230 grain Hybrid and OTM. The 230 Hybrid has the higher BC of the 2. It is a BADDDDDD bullet. It hits harder than any other 30 cal I know. I have run the 230 Hybrids and the Hornady 225 BTHP. The 225 BTHP requires a 1:11" twist. The 230 Hybrid is a longer bullet, and needs the 1:10" twist. I have run both bullets out past 1 mile in the 300 WM and 300 RUM. For ultra long range engagement, the 225 and 230 work very well. For your medium engagements (600-1000 yards), the 208/210's work well also shooting a little faster and flatter. But the 225 and 230 really shine out past that with the higher BC's. If you build a 300WM with a 1:10" twist, the 230 would be a good choice. The Berger twist rate calculator shows a 1.37 stability factor. The old chart used to say 1.4 was minimum, now it says 1.5 is minimum. But the 1:10" will work just fine for that bullet. It won't hurt to go with a 1:9 or 1:8, if you wanted.