Make a 50 BMG handgun ... now that's about up to 2800 ft/sec .... and plenty of energy ... I have seen people shoot homemade ones and it looks like the gun weighs about a ton (almost has to w/o a fore-grip). I've given some thought to making a 50 bmg but, in my case, wisely opted not to.
Or, more tame, and a better handgun fit, but still freaky 50 cal beowulf ... still considering making this one ... with my own loads.
Or the 50 cal S&W monster .. and it is a monster too .. I've shot one and would not want to shoot one again (I cut off my thumb a few years back and its not up to holding this gun due to slight nerve damage; I did not shoot their "reduced recoil" ammo but would not want to either).
The Dillon seems to be rather manageable ....
But lets face it ... you're making the Dillon ... have fun !