There is one issue with this, and that is the rim of .32 ACP ammunition is often too small to support the case in a .32 S&W Long chambered revolver and will simply fall into the chambers causing a problem with ignition. Sometimes, due to SAAMI and manufacturing tolerances it will work! However I would hesitate to try this in a pre WWII revolver. Many will point out that the .32 ACP nominal maximum pressure is greater than that of the .32 S&W Long, it's pressure limit is identical to the .32 H&R Magnum, and S&W has manufactured many revolvers for this cartridge, and many have also been re-chambered for it with no issues whatsoever.