This may already have been covered, but I was wondering if there are any .458 Wildcatts bases on the Ultra Mag cases that will function in a standard length Winchester M70?

blackfoot...welcome to the forum, a great place. As for your question, do a search for 470 AR and follow the threads. I have read some of them and it appears that they work on a standar length action, or possibly a .375 length. If you have a M-70 that is no problem since most M-70's are built on a .375 length actoin to begin with, with blocks put in the magazine box for shorter rounds.

the 458 AR is a 3.35" oal, 2.55" case, that has more case capacity than the lott, and fits right into a standard action.

see the "mission accomplished" thread for quite a bit more info

I found a guy at a recent trade show whom is making a .50 wildcat on the .300 Rem. Ultra Mag.

You can check out his products at www.crossoutdoors.com