Re: 338 RUM bolt head ?
If you're talking single shot, it's a long list.
Start with the .244 H&H Mag, and go up to 470 Capstick, in various length belted mag cases. This includes the short Remington belted's (6.5mm and .35 cal), all the Win Mag's (264 thru 458, as well as 375/416 Taylor, 358 Norma), all the full-length H&H-based rounds, like 300/340/375 Weatherby, 300/375 H&H, 8mm/416 Rem, 7mm STW, 358 STA, 458 Lott etc.
Then go back and include the WSM's and RSAUM's as well as the other caliber RUM's.
The 322 Rigby Nitro will fit as well, if you want obscure.
And then there's wildcats....
If you want it to feed, you probably will have to stick to the RUM's, though 404-based cartridges might very well work. They have similar dimensions.
Happy spending! [img]images/icons/grin.gif[/img]