I have a Colt New Pocket that is chambered for .32 Long Colt. The mighty mite is shown here with a Colt New Service Model 1909. The .32 Long Colt cartridge is also seen here with the .45 Colt and .22 Long Rifle for comparison.
Bought the Colt New Pocket at a Dallas Market Hall gun show years ago just for fun, mistakenly expecting to be able to use .32 S&W Long in it. They won't chamber though.
So, hunted about for some proper ammunition for the little revolver. The revolver uses .32 Short Colt and .32 Long Colt interchangeably.
Some chronograph tests of .32 Long Colt and .32 Short Colt ammunition.
Remington .32 Long Colt 82 grain lead round nose
783 fps MV
112 ft./lbs. ME
72 ES
24 SD
Winchester .32 Short Colt 80 grain lead round nose
763 fps MV
103 ft./lbs. ME
54 ES
19 SD
Some Aguilla .32 S&W ammunition chronograph tested on the same day.
Aguila 98 grain lead round nose fired in the Colt Police Positive.
728 fps
115 ft./lbs ME
37 ES
16 SD
Aguila 98 grain lead round nose fired in the Smith & Wesson Model 1903
631 fps MV
87 ft./lbs ME
50 ES
20 SD
A .32 S&W Long cartridge flanked by .32 Short Colt and .32 Long Colt cartridges.
The .32 Long Colt as well as the .32 Short Colt may be fired in a .32 S&W Long revolver with perfect satisfaction. I've tried it in a Smith & Wesson Model 1903 on hand here. Cartridge cases do not split or even display undue distortion and may be subsequently sized and reloaded with ease (I handload for the .32 Long Colt). Pressures generated in all these .32 revolver cartridges are quite low. Accuracy of the .32 Colt cartridges in a .32 S&W revolver is quite good out to 15 yards.
While the .32 S&W Long cartridge will not chamber in the .32 Colt chamber, the actual dimensional differences between .32 S&W Long and .32 Long Colt are minimal.
.32 S&W Long
Bullet diameter: .312
Neck diameter: .335
Base diameter: .335
Rim diameter: 375
Case length: .93
Cartridge length: 1.27
.32 Long Colt
Bullet diameter: .313
Neck diameter: .313
Base diameter: .318
Rim diameter: 374
Case length: .92
Cartridge length: 1.26
As may be seen, it's the neck diameter differences between the .32 Long Colt and .32 S&W Long which precludes the ability to load .32 S&W Long cartridges in a .32 Long Colt.
The .32 Short Colt seen in the photograph above uses a heeled type bullet. The .32 Long Colt in the photograph uses a hollow base bullet. Both styles of bullets fill the bore of the .32 Smith & Wesson revolver which gives pretty good usable accuracy.