I like rifle/shotgun combinations. One of their virtues is that sometimes you can get sub-caliber inserts to safely use ammunition other than that for which the rifle barrel is chambered. At one time I owned a Savage 24F combination with a .30-30 barrel over 12 gauge, a most useful pairing. I "invested" in several subcaliber adapters for the .30-30 barrel so I decided to see what would happen when shooting a .32 S&W Long and/or .32 ACP in a long barrel.
There are several reasons why someone might do this. The primary one is to use the rifle barrel on small game, "targets of opportunity," so to speak. All deer hunters occasionally are driven crazy by squirrels bouncing around in the leaf litter near a stand; yet would prefer not to use the shotgun barrel because of the noise.
Either of these two rounds when fired from the long barrel of the Savage were certainly quiet enough: the noise level from either round was somewhere between a .22 LR and .22 WMR out of a rifle. Definitely much quieter than a handgun, any handgun. The .32 ACP was slightly louder than the .32 S&W Long revolver cartridge. I didn't have any .32 Magnum on hand but I'd be willing to bet, based on the figures below, that it too would be pretty quiet. A .32 Magnum adapter (or one in .327 Federal) would safely shoot the shorter rounds in it, too.
I also tried some .32 S&W short, stuff my father-in-law had left in his gun cabinet when he died. This was headstamped "UMC," not "REM-UMC." I realized on shooting it that it was loaded with BLACK POWDER, and absolutely had corrosive primers as well. Half the ones I tried were duds, too. God knows how old it was: since UMC got eaten by Remington well before 1920, it was well over 80 years old and likely much older. My father in law was a man who never threw anything away.
Here are the numbers on the average velocities for each caliber I tried. Surprisingly the .32 ACP was higher, but that was a 71-grain FMJ as opposed to a 98 grain LRN. Mean energy figures for each are 176 foot-pounds for .32 ACP, and 179 foot-pounds for .32 S&W Long. No real differences.
A .32 Mag would clearly be marginal for deer, but at close range with perfect shooting it would work. Given the wimpy energies, though, a bigger bullet would be in order.
One major drawback—one that certainly was predictable—was that the bullets from the pistol rounds didn't impact anywhere near the same point of aim as did those from the .30-30 ammunition. It would take a fair bit of "load development" and/or "Kentucky windage" to figure out how to hold the crosshairs on a small target. In the end, though this was an interesting experiment, it really wouldn't be a practical thing to do in the field.
I would like to try this with my drilling, but a sub-caliber adapter in 8x57JR made to shoot either of these two calibers would be a costly proposition; and the groove diameter of the drilling's barrel is 0.318" which is substantially larger than the bullet diameter of either .32 pistol round. It's likely accuracy would be pretty bad.
My drilling, as are most of them, has shotgun barrels chambered for 16 gauge. This isn't always easy to find: the "Little Skeeters" shown above will permit me to use the far more common 20 gauge in it when 16's can't be readily obtained.
Range Results:
.32 ACP .32 S&W LONG
1052 914
1069 915
1078 907
1046 903
1073 909
1051 906
1077 902
1029 899
1022 887
1060 916
MAX 1078 916
MIN 1022 887
AVG 1055.7 905.8
SD 19.51 8.75
VAR 0.02 0.01