Largest cartridge, OR largest caliber? I'm always confused when someone ask me that question, because many seem to refer to "calibers" when they mean cartridges.

I designed a line of "rimmed" cartridges, then having them chambered in the Valmets 412's as "custom guns/bbls.,

left to right: .416, .375, .338 and the 30-06 for comparison

I built two 416's as "experimentals" one had problems and i never built another. I did build quite a few 375's in combo's and DR's, and they worked out very well. I also built a couple 338's and still have one around here in a combo...

There were others, but those are the most powerful...

The cartridge i liked best, is the "improved" chambering i came up with for the 9.3x74R. You can see it compared to the factory 9.3x74R in this pict.,

You can fire factory loads in the chamber, then reload the "improved brass" for a bit more power, as after fireforming it to the larger chamber, the case will then hold a bit more powder.

I did all of this for my own purpose, long ago, and do NO work for anyone else, or even play with these cartridges any longer. I've moved on to different things, but i still enjoy shooting them...

DM