Since 300 H&H's are hard to come by, can a 30-06 be opened up and punched out to 300 H&H. I am looking at a Remington 721 in 30-06 and was wondering if this is possible to accomplish?
Or am I better off, finding a used Savage 110 300 winchester magnum and rebarelling that?
With a 721 your better off throating the '06 to take a 200 gr Speer SP seated out so the base of the bullet is at the base of the case neck. That maximizes case capacity. Then with 180, 190, 200 and 220 gr bullets over H4831SC you can readily duplicate .300 H&H velocities with the 24" barrel of the M721, all within safe operating pressure.
The more tapered case of the .300 H&H may present feed problems with the magazines made for the minimum tapered .300 Win Mag. There are .300 H&Hs out ther that can still be found; 721s, 700s, FNs and of course M70s. I would find one of thhem. You may pay a little more for it up front but it would be less probably than converting something else to .300 H&H. The .300 is a fine old cartridge but then so is the '06.
Larry Gibson