Handgun Cartridge Names By Mike “Duke” Venturino

A logical question often asked by newcomers to the sport of handgun shooting is as follows. Why do .38s shoot .357-diameter bullets? Why the confusion?

We must go back in time to find some answers. When Colt brought out their first successful revolvers in the late 1840s, they were labeled .44s. Shortly thereafter, the extremely popular .36 caliber revolvers came about. In those days, a handgun barrel’s caliber was set by its bore diameters instead of groove diameters. That’s why so-called .44 cap & ball Colt revolvers fired balls/bullets of 0.451/0.454″ in diameter. Continuing this thought, the proper ball/bullet size for .36 revolvers was 0.375″.

So, how does this pertain to handgun cartridges being named improperly? That came about with the development of metallic cartridges. In the early 1870s, Colt had thousands of parts from their now obsolete cap & ball revolvers. Should they just junk them, or should they figure out a way to turn them into cash?This photo shows several .38 Long Colt cartridges handloaded by Duke. The far left one is loaded with a 130-grain heel-base bullet from a Rapine bullet mold. At left is one loaded with a hollow-base 150-grain bullet also from a Rapine mold.

Origins

And therein lies the origin of cartridge conversion revolvers. This wasn’t just limited to Colt revolvers; some gunsmiths also got in on the act. Using barrels originally made for their cap & ball revolvers required the new metallic handgun cartridges to carry bullets similar in diameter to cap and ball projectiles.

So, some bright light decided revolver bullets should be made with two diameters. The main bullet segment would be full size in the same diameter as the outside cartridge walls. Then, the base part of the projectile was made small so as to fit inside the case walls. These bullets came to be unofficially named heel-base.

Lead alloy bullets need lubricant, so knurling or grooves were put around the outside portion of heel-base bullets, and bullets were dipped in melted lubricant.

Sometimes, no knurling or grooves were applied. Instead, a card wad (thin wafer) went over the black powder, then a one-eighth disk of lubricant set atop the card wad and finally, a heel-base bullet seated. I actually have some old factory .44 Colt loads assembled like that. I pulled some apart to examine them.

There were many of these early metallic handgun cartridges, but space won’t allow all of them to be detailed. If the above paragraph has you confused, just look at a round of modern .22 Long Rifle. They are still made with heel-base bullets and dipped in lube.The first newly designed revolver for .38 Colt was that

.22 Long Rifle

So, let’s use .38 Colt as our primary example. In the book “U.S. Cartridges and Their Handguns: 1795–1975,” the author, Charles R. Suydam measured outside bullet diameters of original .38 Colt rounds from various manufacturers. They ranged from 0.376″ to 0.381″ in diameter. Mr. Suydam didn’t want to ruin valuable antique cartridges by pulling some apart, so he did not provide measurements for the heel-base portions. The ones I’ve measured have been in the 0.356/0.358″ range. Also worthy of note is that .38 Colt, at this time, used a case length of 0.88″, give or take a thousandth or two. Thus, .36 caliber revolvers came to be called .38s after the advent of metallic cartridges. Things were about to change.

In the early 1890s, the U.S. Army desired to move from its large .45 Colt cartridge to the smaller .38 Colt. But by that time, the era of heel-base bullets had passed in favor of bullets fitting inside cases. Some factory loads for obsolete cartridges still have heel-base outside bullets, but none were developed after the late 1800s. With the Civil War experience of shooting undersize hollow base Mini Balls in rifled muskets and counting on them to expand to grip rifling, the U.S. Army decided such a system should work for .38 Colt. It did.

Therefore, hollow-base bullets of (nominal) 0.357″ were developed to set with their full diameter inside cartridge cases. In order to accommodate the same powder charge of 19 grains used in the .38 Colt heel base ammunition, case length was increased to 1.03″ (again nominal), and we get the new name of .38 Long Colt. However, I’ve never viewed any vintage revolver stamped “.38 Long Colt.”

Performance

Let’s cogitate a moment. How accurate will a revolver be when a 0.357″ bullet is shot down a barrel measuring somewhere between 0.370″ to 0.375″ across its rifling grooves? Well, let me tell you; they can be pretty darn accurate. I’ve owned Colt Model 1877DA .38 Colt revolvers and still have a Colt Model 1861 replica converted to .38 Colt using the original large-diameter barrel. They have been fine shooters with my own home case hollow-base bullets and even better with 148-grain Speer hollow-base wadcutters.

How does this discourse on .38 Long Colt explain why the .38 Special wasn’t named .35 or .36 Special? It’s because the .38 Special cartridge was simply the .38 Long Colt lengthened to 1.16″. All other dimensions were the same. In the 1930s, someone at S&W based in reality named their new magnum cartridge .357 Magnum instead of .38 Magnum.

So, if you wonder why cartridge names don’t fit, it’s because back in the early days of metallic cartridges, things were done and named differently from today.