Do any normal factory loads make the power factor? If they do, then you might have a case. If not, then you're SOL. The .40 was developed for several reasons, among which was the inability of some burly gentlemen to handle the recoil of a (real) 10mm, or .45 Hardball. (Although my 19 year old daughter seems to do OK.)
USPSA no longer allows building handgrenades by attempting to load sub-caliber rounds up to "Major." The whole point of which was "gamesmanship" and trying to gain an "unfair advantage" by creating a "major" round with less recoil than the .45 ACP. If a certain caliber is specified, then that's it. 'Dems da rules, 'n if'en you don't like it, FIND ANOTHER GAME.
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Fred J. Drumheller
NRA Life
Nra Golden Eagle