Re: the .50GI.  It's an interesting cartridge, definitely intended for the momentum fan who thinks velocity is pretty meaningless.  It pushes a 300gr bullet at a sedate 700fps, intending to hit more like a sledge hammer instead of a ball pein.  But this would make all those "don't make a .46" fellas happy, eh?  and you can easily convert any standard .45ACP-chambered 1911...and swap back and forth.