Mike Irwin has explained the reason most experts discourage the use of .32 ACP in revolvers - the old breaktops and other old revolvers just won't handle it. .32 S&W runs about 14k psi pressure and most of the old cast iron guns will take that. But when you up the ante to the 21k and full jacket of the .32 ACP, the old guns literally get bent out of shape.
Jim
Jim