It is one of my all-time favorite cartridges, a round with an interesting history. The .45 Auto Rim was developed by Peters Cartridge Company in the period right after World War I ended. More than 300,000 Colt and Smith & Wesson revolvers came out of Gun Valley during that war, all chambered for the then-standard .45 ACP pistol cartridge. That's a rimless cartridge that needed the ingenious half-moon clip to hold the cartridges in place in the cylinder. The system worked quite well and the revolvers filled in for the standard .45 Auto pistol when there weren't enough of them to be had. When the war ended, the 1917 Colt and S&W revolvers were declared surplus—many were sold through DCM. The half-moon clips that made the system work were widely available, but some shooters grumbled about loading and unloading the pesky three-shot crescents of sharp spring steel.
Enter the .45 Auto Rim. Introduced in the mid 1920s, the Auto Rim was nothing more than a .45 ACP case manufactured with a wide, extra-thick rim. It is useful—with no need for clips—in either Colt or S&W .45 ACP revolvers with swing-out cylinders. By the time the American ammo industry went on three shifts to feed the nation's armed forces in World War II, several makers—Remington, Peters, Western, Winchester and US Cartridge—were producing .45 AR ammunition. The cartridge was popular enough as to be returned to full production after the war. But in the intervening years, the cartridge lost popularity for many reasons, not the least of which was the introduction of the full-moon clip by Ranch Products.
The .45 Auto Rim still has a cult following, but none of the major makers produce the cartridge. For a time, it looked like Black Hills was going to do well with .45 AR in a new loading. Jeff Hoffman liked the big-bore revolvers and tried a 255-gr. LSWC load that pretty well equaled .45 Colt ballistics. The load did not sell well enough to justify continued production; it was quietly discontinued. Cor-Bon listed several .45 AR loads for a few years, but they are now missing from the company listing. It was looking like this old round was going to be a handloader-only proposition.
But then I discovered that Double Tap Ammunition offered the caliber. They not only make it, they do so in no less than four different types. For the speed freaks, the company offers a 160-gr. Barnes copper bullet. Original Auto Rim ammo came with 230-gr. bullets and so does a pair of Double Tap loads, an FMJ and and a JHP. But the best of the breed—in my humble opinion—is a 255-gr. Keith LSWC, which comes out of a six-inch revolver barrel at a quoted 900 fps. I have handloaded exactly this combo for personal defense purposes—a sure fight-stopper. Some people are uncomfortable with handloads for personal defense. If they go in harm's way with a .45 ACP revolver, they can load it with their choice of these factory loads from Double Tap.