I have owned a few 300 win mags, a 300 weatherby, 300 rum and a 300 shorty.
Given one rifle to do it all in NA and everything in Africa short of buffalo, ele and rhino I would build a 300 RUM with the following blue print.
My rum is a model 70 mag action, 24" mike rock #3 barrel, Talleys lightweight mounts,Williams bottom metal, Jewell trigger, Leupy 3.5-10x40, Echols Legend/Edge stock. All up, short ammo it runs a hair under 8lbs. I wouldn't want to go much lighter with any 30 cal mag. It also spits out 180 gr bullets around 3300 fps give or take with loads under max. You may or may not get that out of a 26" tubed Weatherby but you still will have to deal with expensive brass, a belted case, and the down sides to running high pressure loads.

Last edited by BWalker; 11/16/09.