Instead of wildcatting a cartridge, just buy a new 50 cal S&W. I've got to say, that the 44 mag would never had been popular if it wasn't for Dirty Harry, and I believe S&W credited the movie for the majority of it's sales. The Auto-Mag was shown by Inspector Callahan not too long after. People would have been carrying harpoons, if they could strap them to their hip, to copy Harry.
I'd rather stick to my 9mm, as far as faster firing and aiming.