Shadow Catcher, wouldn't moon clips work? I've never used them and I know they would be a pain w/ a single action but ifn you wanted to use up the ammo they might be worth it, at least for practice. BB
I think Bonesteel got it right - the total headsapace thing won't work.
I read some years ago an article by Skeeter or one of the greats about taking a Ruger Blackhawk with a .45 ACP cylinder as a hiking/trail gun, and carrying a few officers model mags with hot .45 ACP ammo as a means of fast reloading. Struck me as a fine idea - and I have a few New Vaqueros - any of which would be a great hiking/trail/riding pistol, almost as good, maybe better, than my 1911.
Let's be honest - I think a 250 - 300 gr .45 Colt load is better than a .45 ACP load of any variety, but I have a boat load of .45 ACP as well, and it's a neat solution to a non-existent problem. I'd love to have one for my short bbl'd .45 . . but I can get by for another 30 years without it.
Maybe someone will get an itch to make them and market them - then I'll buy one.
Shadow Catcher