Here's what I'm thinking: load 30 to 50 rounds with 55.0 grains of powder and the bullet seated to 3.405", clean the bore, and tighten the action screws. Fire five rounds off my Lead Sled, holding the rifle the same way every time. If they're still double grouping, I'll shoot five rounds off my specialty pistol rest and a sandbag. If that doesn't work, I'll run inside and adjust my seating depth. Lather, rinse, repeat until I find the answer.