If you look real close at the standard 1911 you find that at the bottom of the chamber, to allow for feeding, the brass is very poorly supported. And with warm loads, cases bulge... Some become un reloadable... but the military don't care...
When I was very young, there was a push to use the .45 case necked to .358 for the "38" stage of competition. Powder puff loads and the same frame to practice with, just different slide/barrel/magazine(??) assemblies.
First "big power" fix was to cut down .30/'06 mil surplus brass(I said this was an old game) and neck ream to make a case with alot stronger "head"... Called .45 Super" or .451 Magnum... or smaller calibre... .308 cases work fine too. (Or any other .473 Mauser head.)
At the same time, there are custom barrels and feed ramps where the case is fully supported all the way around. Better for "big power."
You want 41? O.K. (Or .40). There was a 'smith in TX doing the .451 for law dogs. No good idea where to look for other calibers. Do you want the fullest power, or just a smaller bullet and standard .45 preformance? It just takes money. Do some web searches and look in the back of Gun Digest Annual at the directory and you might find someone doing what you want. Just takes money. LUCK.