10mm Auto Ammunition – 10 Things You Should Know

Please check out our other review of 10mm auto ammunition found here.

10mm Auto Ammunition
10mm Auto Ammunition

USA – -(Ammoland.com)- Despite its thirty-plus years of existence, only now is the 10mm Auto Ammunition getting its due. The future is looking to be good for the 10mm auto ammunition, with new pistols being released to the market, turning smoldering coals into a fire.

10mm Auto Ammunition

The 10, however, is still new to many and whether you like it or not, now is as good a time for a refresher.

  1. Col. Jeff Cooper
    Col. Jeff Cooper, 100mm's OG

    If one person is responsible for the 10mm Auto’s existence, famous writer, and pistolero Col. Jeff Cooper is the guy to blame. Conceived as a magnum cartridge for semi-automatic pistols, the 10mm was suggested by Cooper and in cooperation with Michael Dixon and Thomas Dornaus to produce a pistol rugged enough to handle the round. The Bren Ten pistol that resulted became a cult classic, despite lackluster sales in its 1983-86 production run.

  2. The 10mm had a brief career as the FBI’s cartridge of choice. In the aftermath of the 1986 Miami FBI Shootout, the FBI decided to pick a new cartridge that would be in a platform that reloaded faster than the 38 Special revolvers and with more punch than the 9mm pistols fielded on that fateful day. The 10mm threw a bigger bullet faster than those rounds, and it was built for faster reloading semi-auto pistols. Large framed pistols like the Smith & Wesson 1006 series were adopted. This trend didn’t last long, however.
  3. The 10mm gave birth to the 40 S&W. In short, the adoption of the 10 by the FBI was a knee-jerk reaction. The round’s recoil and blast made it hard to shoot well, and the round was loaded lighter in response. By 1990, Smith & Wesson used this downloaded 10mm and shortened its case to fit into the grip of a conventional 9mm pistol. Hence, the 40 S&W was born. The 40 is still powerful, but it boasted lower recoil and could be chambered in traditional auto pistols. The FBI was quick to adopt this round, and many police agencies followed suit.
  4. The 10mm is based upon a rifle round. The .30 caliber Remington was a medium power cartridge like the 30-30 Winchester round. The main difference is the 30-30 has a distinctive rim for extraction, while the 30 Remington has a recessed rim for easy use in auto-loading rifles. The 30 Remington brass is shaved down into the straight-walled 10mm Auto round.
  5. The 10mm is controversial in the self-defense role. The 10mm propels a 40 caliber bullet about 180 grains at between 1200-1400 feet per second, rivaling or surpassing the 357 Magnum revolver cartridge depending on your load. Thus, there is something of a bias against the 10mm as being too powerful for defensive use. The famed trial of the late Harold Fish is a firm example of this. Fish’s story had some inconsistencies, but during the trial, his claim of self-defense was challenged because of his use of a 10mm pistol. The prosecution claimed Fish intended to kill by using such a powerful handgun.
  6. 10mm Auto Ammunition with pal, .357
    10mm Auto Ammunition (L) with close cousin pal, .357
  7. The 10mm excels in field use. Pistols chambered in the round have proven themselves adept at both handgun hunting and protection in the bush. Over a conventional medium framed magnum revolver, 10mm pistols, on the whole, carry more ammunition and be lighter on the hip. Those saved ounces matter on a long rendezvous.
  8. The concealed carry market has a 10mm undercurrent. The vast majority of 10mm pistols are large framed handguns based on the CZ75, 1911, or full-sized 10mm Glocks. However, there has been a trend toward stuffing the 10 into something more compact. The Glock 29 subcompact pistol has been around for a while and is a proven performer. Others like the newer EAA Witness Compact are out there, and the continuous caliber debate will undoubtedly spur the new interest in the round into new and dangerous territory.
  9. Ammunition variety is expanding, but still elusive on shelves. Just about every ammunition manufacturer has a few 10mm Auto loadings out there. You can get a multitude of full metal jacket practice ammunition to defensive hollow-points to flat-nosed heavy grain bear loads. Unfortunately, finding anything other than practice ammunition at your local sporting good stores can be elusive. A few short years ago, it was rare to encounter any 10mm ammunition at all, so the round’s stock is improving.
  10. 10mm factory ammunition can disappoint. What do I mean by that? Ask any 10mm aficionado, and they will tell you that factory 10mm ammo is loaded lightly. The reason for this has little to do with liability, but the fact that data used with the FBI’s lighter-loaded 10mm ammunition is used rather than the actual Norma specs that Cooper envisioned. This is especially true, in my experience, with practice ammunition whose velocity is hardly different from 40 S&W. Velocity is substantially raised when using defensive hollow-points and bear loads.
  11. Pistols are hard to find and more expensive. The web has everything you could want in 10mm, but it is hard to translate it to stores. Big box operations and mom-n-pop shops are more likely to stock the current mainstream handguns in familiar defensive calibers like 9mm, 40 S&W, or 45 ACP. Despite the new interest in 10mm, seeing one on a shelf is unusual. What isn’t usual is the higher sticker price you can look forward to paying when you do find one. When power is the name of the game, it is easier to find magnum revolvers and ammunition to fire them.
Terril Hebert
Terril Hebert

About Terril Hebert:

Terril Hebert is a firearm writer native to south Louisiana. Under his motto—Guns, Never Politics—he tackles firearm and reloading topics both in print and on his Mark3smle YouTube channel, where he got his start. Terril has a soft spot for ballistics testing, pocket pistols, and French rifles. When he is not burning ammo, he is indulging his unhealthy wildlife photography obsession or working on his latest novel. Scourge of God, published in 2017.

  • 8 thoughts on “10mm Auto Ammunition – 10 Things You Should Know

    1. I enjoy everyone conversations about the different firearms and the almighty 10 mm. The different types of pistols and their ammos’ are just that, TYPES. They all give us a big range and answers to questions, otherwise if we do not try all of these types, we will never know what we are capable to handle. If a 90 year old Grandmother can operate successfully a 3″ .357 Magnum revolver and protect her grandchildren and herself, Please Beware! That Grandmother is a much great access, one of the best, but if all she can handle a .22 Magnum with the ability to do Home Defense to its best; watch out. Still the Greatest !!! The 10 mm in the Glock 20 and 29 Gen 4 are my taste range and I use many different types. They all work. Just like tools for the garage and shop. Please stay safe always and practice hard. Thank you, everyone !

    2. I have been carrying a Smith and Wesson 1006 since 1990 and have never had a problem carrying it. It’s not heavy or uncomfortable in anyway. The FBI went away from carrying the 10MM after adopting it because the less sturdy agents couldn’t handle the recoil. By going to the FBI lite version of the ammunition, they defeated the entire purpose of the study and change over to a more powerful, quicker to stop the criminal round. By lightening up the ammunition’s load they moved away from the purpose of the more powerful round and so abandoned the entire study, wasting our money and endangering the lives of agents in the future. They have even dumped the .40 to go back to the 9MM which wasn’t effective enough in the shoot out that start the study to begin with. Agent were still allowed to carry the 10MM as a personal weapon as long as it was on the approved carry list which included the S&W 1006 and 1076.

    3. As a handloader, one thing that intrigues me about the 10mm is that at IPSC Major power factor, it’s loafing, while 9mm, 38 Super, and 40 S&W are working really hard.

      Have loaded 40 S&W to Major for years, but am interested in working up cheap 10mm Major loads using lead bullets (in the appropriate barrels) at about 1000 fps.

      Anyone have experience with this?

      1. One way to make such a round is to buy an aftermarket conversion bbl for your G20. I have Wolf aftermarket 10mm, 40 S&W, and 357 Sig bbls for my G20. The 40 S&W bbl is throated just as long as the 10mm bbl. This allows the overall length to be the same. I can safely get the same velocity with the same bullets and powders in the 40 as I do in the Wolf 10mm bbl. I use Winchester small pistol mag primers and 40 S&W cases are free for the picking at most ranges. It doesn’t get a cheaper than that.

    4. I shoot and CCW a glock 29 and love it. It is light weight and is enough power to protect me and my family against almost anything. Honestly it’s just as a irate as my .40mm .9mm .45mm glocks. With a lot more stopping power. I want a gun that is going to safe our life’s and have the confidence that if I have to use it it is going to work and work very well!!;) Kust my two cents you all have a blessed day!!

    5. 1. Lackluster because they couldn’t get magazine production going.
      2. Better tactics and using their 357s could have brought better results.
      3. The 10mm is not conducive to long range sessions in full power mode and the female and small male agents had difficulty handling the full sized guns.
      4. Coincidence.
      5. He had incompetent counsel.
      6. N/A
      7. I concur.
      8. The Glock 29 is not a “subcompact” pistol.
      9. The same can be said for any of the Magnum revolver rounds.
      10. Because most people want to shoot their guns and after two or three magazines of fullhouse 10mm most people are ready to shoot something else; myself included.
      11. There is this new thing called the internet which negates this concern.

    6. If the 10mm Auto cartridge is only now getting it’s due among auto pistol shooters maybe there’s a chance the .41 Remington Magnum Revolver cartridge will finally get it’s due among revolver shooters?

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