isn't the standart twist 1:12 on an H&H ??
I know it's 1:14 on a 416 Rem and Ruger uses that on the Rigby.
The SAAMI spec on a 416 Rigby is 1:16.
If 400 gr will stabilize at 1:16 in a rigby (CZ uses this twist) then I can't see any problems with 300-400 gr out of a 1:12 or 1:14.
