10mm

The 10mm Auto is the cartridge the .40 S&W wishes it could be. It’s bigger, faster, and hits substantially harder — a true high-performance pistol round that sits in genuinely impressive ballistic territory. It was watered down once, declared “too much gun,” and spent years as a niche favorite. Then shooters came back to it in force and the industry followed. The 10mm is having its moment, and if you’ve ever shot one properly, you understand why Jeff Cooper was so irritated about the whole situation.

Jeff Cooper — the father of modern pistolcraft and the man who gave us the four rules of firearm safety — conceived the 10mm Auto in the early 1980s. The cartridge was developed by Norma Precision of Sweden and introduced in 1983 with the Bren Ten pistol. The FBI adopted a downloaded version of the 10mm after the 1986 Miami shootout, then found that the full-power load was too demanding for many agents to qualify with. The result was the .40 S&W, introduced in 1990 — essentially everything the FBI wanted without the part that required actually being able to shoot it. The 10mm lived on in niche circles, championed by hunters and serious shooters, and began its comeback in earnest around 2015 when the handgun hunting and bear defense markets started demanding it.

A full-power 10mm Auto load pushing a 180-grain bullet reaches approximately 1,300 feet per second and delivers around 676 foot-pounds of energy — more than most .357 Magnum loads and getting into territory where you start having meaningful conversations about hunting and bear defense. Lighter 135-grain loads can exceed 1,600 fps. The full-power 10mm is a different animal from the FBI’s downloaded version and a dramatically different animal from .40 S&W. These are not the same cartridge with different branding. The gap is real.

Handgun hunting for deer and hogs. Bear defense for backcountry hunters and hikers who want more than a 9mm and less than a hand cannon. Competition — the 10mm naturally makes USPSA Major power factor with full-power loads. Self-defense for people who want maximum performance in an auto-loading pistol. The Glock 20, which holds 15 rounds of full-power 10mm, has developed a serious following among hunters who want a capable backup gun. It’s a legitimate hunting handgun that also goes in a holster.

Pros: outstanding energy, flat shooting, effective on large game, and available in excellent pistols from Glock, Colt, Sig, Dan Wesson, and others. The ballistic versatility is real — commercial loads range from mild practice ammo to full-power hunting rounds, so you can tune the experience to what you need. Cons: snappy recoil even in full-sized pistols, more expensive ammunition than 9mm or .40, and guns chambered in 10mm tend to be larger and heavier because they need to be. This is not a compact carry cartridge. It is a purposeful cartridge for people who know exactly what they want.

The original Bren Ten pistol — the gun that launched the 10mm — had such significant production problems that many pistols shipped without magazines. This did not help the cartridge’s early reputation. Colt eventually saved it by introducing the Delta Elite 1911 in 10mm, which gave the cartridge a reliable, quality host and kept it alive long enough to find its audience. The Glock 20 later became the most popular 10mm pistol ever made, which is exactly the kind of outcome Jeff Cooper probably would have found both satisfying and predictable.

Arms East carries 10mm pistols and a selection of ammunition from practice loads to full-power hunting rounds. If you’re coming from .40 S&W and curious about what you’ve been missing, come in and we’ll talk you through it. If you’re a handgun hunter or heading into bear country, this is genuinely the conversation you should be having. We’ll help you find the right gun and the right load for what you’re actually going to use it for.