I just do not see how this can work for an extended time. I assume that the breech face of the 40 slide differs in size than the 9mm breech face. the extractor must be different in the 40 simply beause the case is a different size than the 9mm. Also Loading 9mm rounds in a 40 magazine, I guess that would work but would u really wanna trust your life on that??
just my 2 cents