Hey Bid O, good to see you're still out there and with innovative thinking as always...........You could do this on a falling block action and have a very compact T-rex killer, or if you have your sights set on a bolt, go with a bull pup design and keep the weight between the hands and make it more controllable. A 24" 50 BMG on an upsized #1 action would be practical, and the single shot would not be a disadvantage because you would have all the time needed to reload while managing the recoil and getting the sights anywhere near "on target" again. This will also work very nicely as a flame thrower..............Kill and cook in milliseconds............HHHMMMMMMM