Casscade; I have a 13 lb, 27 1/4" barrel, rifle that I've started working up. So far, 2760 fps with the 300 smkhp and 110 gr of H-5010. Very mild, 3/4" 5 shot @ 100yds. I believe I can make 2800 fps, maybe not with 5010 though. I expect to get down to 1/2 moa. I don't think I have enough barrel to get 2850, pushing hard.
IMO, a 5.5 is way too light for a barrel over 26" in this caliber, let alone 30".
JECustom is right, it will be unpleasant without a brake, and the brake is unpleasant to hunt with.
Chawlston, ditto jwp's questions. I haven't had any luck with Retumbo. What primer do you use? 3000 fps is a great neighborhood!
jwp, I get 3-5 firings before the pocket gets too loose.
There's been a lot of good discussion pro and con about the Wby calibers and guns recently. The MK V's are my favorite actions, and the only factory action that I will build a .378 based caliber rifle on.
Texas State Rifle Association Life Member
NRA Endowment Life Member
A big fast bullet will beat a little fast bullet every time