[Gatofeo]

TONS OF CONFUSION on the .32 Long Colt, .32 Short Colt, .32 Smith & Wesson, .32 Smith & Wesson Long and .32 Colt New Police.

I reload for both of the long versions, and they are NOT interchangeable.
The following is confusing, so read carefully ... may be a pop-quiz later.

.32 S&W Long is the same cartridge case as the .32 Colt New Police. The only difference between the two is that the .32 Smith & Wesson Long was loaded with a fully pointed roundnose bullet. Conversely, the .32 Colt New Police had a flat tip on the bullet (called a meplat).
Note: This applies the bullet or projectile of either cartridge, not the dimensions of the brass case. Both brass cases have the same dimensions and are interchangeable.
The name difference is because Smith & Wesson came out with the cartridge first. Colt didn't want to stamp .32 S&W Long on its revolver barrels, so it had ammo manufacturers put a flat tip on the lead bullet, and named this "new" cartridge .32 Colt New Police -- for the revolver it was chambered within, the New Police revolver.

The .32 Long Colt predates the .32 S&W Long and .32 Colt New Police by about 25 years.
The .32 Long Colt brass case is about the same length as the .32 S&W Long (ne' .32 Colt New Police) but its diameter is much smaller. Consequently, a .32 S&W Long / .32 Colt NP should NOT fit in a .32 Long Colt chamber.
The .32 Long Colt is basically a center-fire version of the .32 Rimfire cartridge. The .32 Rimfire has not been made for at least 20 years. Navy Arms last had them made in Brazil, but that stock is long exhausted.
Old West Scrounger used to offer this Navy Arms ammo, but has not for many years. No one's making .32 Rimfire ammo anymore.
Similarly, the centerfire .32 Long Colt ammo has not been made in about 30 years. I have some Remington ammo, probably made in the late 70s or early 80s. Remington was the last to make .32 Long Colt ammo.

The .32 Short Colt is a shortened version of the .32 Long Colt cartridge. The case is shorter and it uses a slightly lighter lead, pointed bullet with a heel. The bullet diameter is the same as the brass cartridge case, and this short heel is all that is seated in the case. The remainder of the bullet is outside the case.
The bullet's lubrication is also outside the case. Heeled bullets were once common in the older pistol cartridges. Today, the heeled bullet lives on in the .22 Rimfire family of cartridges: a short heel is seated in the case, the remainder of the full-sized bullet and its lubrication are outside.
Scrutinize a .22 Rimfire round and you'll see what I'm talking about.
The .32 Short Colt is still made today, in limited production runs, by Winchester Ammunition -- complete with heeled bullet.
This cartridge will work in a .32 Long Colt chamber, but should NOT be fired in a .32 Smith & Wesson Short or .32 Smith & Wesson Long / .32 Colt New Police chamber.
The .32 Short Colt cartridge is smaller in diameter than the .32 Smith & Wesson Short and Long / .32 Colt New Police chambers. Firing the smaller diameter catridge may result in hot gases escaping back toward the shooter, or split cartridge cases.

The .32 Smith & Wesson is a short cartridge that may be fired in the .32 S&W Long or .32 Colt New Police chamber. It's the same diameter as these longer cartridges and may safely be fired in these chambers. But accuracy may suffer because the bullet has to travel so far before it engages the rear of the barrel (forcing cone).

There is a great deal of confusion surrounding these cartridges.
Basically, if anyone tells you that the .32 Long Colt and the .32 Smith & Wesson Long are the same thing -- beware! That person is equally confused and thinks that the .32 Colt New Police is the same as the .32 Long Colt. They are entirely different cartridges and not interchangeable.

I reload the .32 Long Colt for my Marlin Model 1892 lever-action rifle, and the .32 Smith & Wesson Long for my very old Colt New Police revolver.
Search the net under "Gatofeo" and "Marlin 92" for a very long essay on reloading for the .32 Long Colt cartridge that I wrote years ago.