I think really easy here, Bryce Towsley took the 300 RUM in 1999 and necked it up to 35 caliber. Calls it the 358 Ultra Mag Towsley (UMT).
225gr Barnes XLC 3100fps
250gr Barnes X-bullet 2,965fps
250gr Swift A-frame 3114fps
hard to argue with those numbers or the likely bullet terminal performance...
I may have to use one of the M30's for one of these.

Rich

I like the 30-06; however, the 9.3x62 will do everything an 06 will do, only better. If you think the 06 is IT, take a close look at the performance of the 9.3x62. It is the most balanced factory cartridge I know of.

The light end loads (232 and 250gr) will hold a 6" circle to over 250yds, which is comparable to the trajectory of the 180gr 30-06 load. (The two loads will have almost identical trajectories.) The 9.3 bullet will have 200 more foot-pounds of energy though.

The 9.3 heavy bullet is 320gr, a hundred grains more than a 220gr 30-06.

Unlike the .30's,.35's and 338's (magnum or not) that have been mentioned, the 9.3 is legal most places in Africa for DG.

Because it is not a military round, it is legal in those countries that proscribe military cartridges.

Unlike the 9.3x64, brass is easy to come by, or you can make it from 30-06 brass.

Sorry, Charlie, but the most versatile medium caliber cartridge is the 9.2x62. Kudude

Well talk about reviving an old thread.... since 2002!

After purusing this, seems like the most popular are either a magnum or a 30/06....

In my opinion, the best medium bore caliber, if we are not hunting Alaskan bruins, or some large african game... the most versatile is a plain old 6.5 mm bore....and not a magnum! Say 6.5 x 55, or my favorite..6.5 x 57...

and if someone wants to call that a small bore, then, I follow up with one of the non magnum 7 mm bores...say 7 x 57.....

I don't burn up my testosterone on rifles and gun powder... I burn it up on the opposite sex...

"Versatile" -- You can do prarie dawgs and bear with the 30-06, from about 80 gr. bullets to 220 gr. or maybe more. (I'd have to search.)

But mostly, if you end up out in the middle of BFE (bumfuk egypt) and stop in at a 7-11, mom & pop, "gas n' go" and ask if they sell ammo --

"We don't sell ammo, but Jim Bob has a box of '06 out in the truck. He'd be willing to let you bum a few rounds."