Dave, thanks for the infos.
Master, I remembered today that Wby rifles have a hell of a freebore, in their own wby calibers... and you might have difficulties seating the bullet close enough from the rifling... at least if you intend to feed them through the mag.
If so, a loverin bullet might come handy, specially if you are looking for top speed; they are almost fully supported by the bore, but might still jump the grooves if coming from too far too fast; I don't know, I've never used them.
Yours is the 311291 if I remember:
http://www.lymanproducts.com/lymanproducts/rbulleta.htm
Lyman's drawings are baaad!