I was pondering the other night about turning my .416-Rigby into something in the big bore caliber, like a .500 something or other. Anybody got any suggestions? I already have a .416-Remington mag, .458-Winchester mag, .458-Lott, .475-mag. Any help appreciated people.

How 'bout a .404-.416? .423 is about your only gap besides .50 cal.

You might want to take a look at the photos of Buhmiller's cartridges in this article by Bob Bell. Although the 500 shown on the left is based on a 378 Wby (belted) case, the dimensions of the 416 Rigby (beltless) are basically the same, so it should work.

If I were making a 500 (0.510") caliber wildcat on the Rigby case, I would consider reducing the case taper from the factory spec (~0.019" tpi, as near as I can tell) to somewhere in the 0.009-0.007" tpi range, to allow a longer shoulder on the beltless case. Not looking to increase case capacity, but just to ensure consistent headspace. Hope you'll post some data and photos if you go ahead with he 500 wildcat idea - sounds promising. Good luck.

.411

Run pistol bullets to 400 grainers.

On the Rigby bolt face the 500 A-Square would be a good choice. 460 Weatherby necked up. Dies, brass, loading data are all plentiful.

Yes I am liking the idea of a .50 caliber for a rifle. I do plan on going to the dark continent again soon I hope for Buff/Hippo. I would love to shoot something with a 700 grn bullet too.

Check out the threads on the 500A2 over on Accurate Reloading, there are several reports of it's use on African game, including elephants.

.470 Mbogo