Cartridge of the Week, the 10mm, 10mm Auto

Those who have followed my posts know I have one foot in the past and one barely in the present when it comes to firearms and cartridges. It takes a lot of evidence and time to prove something to me. Nothing like the tried, true and tested. Nevertheless, I cannot argue with the point that somethings are good right out of the box, like the Colt Python, wait there I go again. Another thing that is hard to argue with is physics. Well you can, but people will see you talking to yourself and runaway. When it comes to physics and raw proof, there are few cartridges that rival the mighty 10mm Auto.

The 10mm Auto
The 10mm Auto cartridge was thrust into service due to the death of two FBI agents on April 11, 1986. On that date FBI agents, engaged in a firefight on the streets of Miami with two serial bank robbers and killers. An assailant wielding a Ruger Mini 14 .223 semi auto rifle killed special agents Jerry Dove and Ben Grogan. The glaring problem was that an assailant, Michael Platt, was already shot approximately nine times including a wound from a 9mm that broke his arm and lodged in his chest cavity. This round collapsed a lung and filled his chest cavity with blood yet he was still able to fight and kill two agents.

FBI Special Agents Jerry Dove and Ben Grogan
One suspect, William Matrix, took six shots to succumb to his wounds. Platt took at least 12 shots to bring to an end his actions and his life. Of the eight agents who engaged the suspects, only one was uninjured. Seven were either shot multiple times, injured by shrapnel from bullet impacts, and as stated above two killed. All this after the suspects had been shot multiple times. The guns used by the agents were wheel gun .38 Special .357 magnums, 12 gauge shotguns and 9mm semi auto pistols. Tactically some mistakes were made in the stop but that is only half the story. It should be noted, that the suspects had no drugs in their system.

The result of this event, and later the North Hollywood shootout, would result in at least three major changes in the law enforcement community. The first was the exit of the revolver from the duty belt. This gun had served well but the firepower–amount of bullets that can be fire–had to be changed. Second change, the caliber that most departments used needed an upgrade. Finally, the officers and agents on the front lines needed a caliber as good if not better than the bad guys.

Within a year, the FBI was at work finding the right cartridge. Tests performed on various clothing, barriers, and ballistic gel types resulted in at least three outcomes. It must create quick incapacitation by damaging the central nerve system. It must cause the greatest amount of internal injuries to cause massive blood loss. Twelve to 18 inches of penetration must be achieved and with good bullet expansion.

Coming Soon to CTD – Rock Island 10mm
The goal was to find a cartridge with better external ballistics than the .45 ACP and better terminal ballistics than the 9mm Parabellum. The search resulted in the 10mm Auto designed by a legend in the firearms industry, Jeff Cooper. The 10mm was on the shelves at least four years prior to the Miami tragedy. Of the cartridges tested the 10mm was vastly superior to the 9mm in exterior and terminal ballistics. As far as the .45 ACPs performance, the 10mm’s external ballistics performed well above the .45 ACP. However, in the terminal ballistics it was just marginally better.

Unfortunately, when it came to the internal ballistics the 10mm, it was a third-place finisher. The 10mm’s pressures and subsequent recoil made it a little too hard to tame in a firearm that could contain numerous rounds and adequately wielded by the majority of agents. Some female agents, officers and those with smaller hands and body frames had trouble controlling this monster round. The FBI experimented with a 10mm light at this point. This defeated the purpose and only created a somewhat inept .45 ACP.

Sadly enough the FBI and other agencies ran away too soon from the 10mm Auto. They did so not because this is a bad cartridge, only that a better one was found for their purposes. That cartridge was, and continues to be, the .40 S&W. The .40 has taken the law enforcement community by storm and rightly so, it is a great round. Nevertheless, the 10mm still has a place in that community. It is a great cartridge and for those who can handle what it comes wrapped in and the bark that goes with the bite, it is everything the .40 S&W is just on steroids. As firearms enthusiast we must not let the 10mm Auto go quietly into the night.

10mm Auto – Big Medicine
The Mighty 10mm

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Comments (20)

  1. Glock 29SF, 230 grain hard cast lead, 200 grain hp and 180 grain fmj at the range.. I have all the confidence in the world in this round, the gun and my ability to use them effectively.

  2. My 4’9″ wife has no problem with my G20 and I shoot what I leave loaded in it, Winchester Silvertip which are well north of 600 ft.lbs. I also have some DoubleTap ammo that runs well over 700 ft.lbs and that’s also no problem to shoot. A snubby 357 with reasonably stout loads produces a good deal less power and is a lot less pleasant to shoot. In 15 years I think I’ve had three failures in my G20, all of them were bad reloads, the cheap ammo at a local range.

  3. Thank you all for posting your stories, opinions and statements. I am a 10mm lover because of my cousin (Delta elite) and my grandfather (who had several different handguns) the 10mm is still used on big game hunts with only a few alternate choices such as a 41, 44 magnum etc.

    Keep up the good work!

  4. I own two 10mm guns. A STI Perfect 10 and a Glock 29SF. I think a good comparison is the 6″ Perfect 10 using 155 gr. Hornady Custom XTP ammo shoots 100 fps faster than my Ruger GP100 6″ .357 mag using Hornady 158 gr. XTP. Roughly 1,400 fps vs. roughly 1,300 fps on my chronograph. That is a lot of energy. They are both extremely accurate guns. The main difference is that the Perfect 10 holds 14+1 with the factory mag, and 17+1 with the optional mag. I will take the 10mm over any other pistol cartridge. The kick is not bad, and the smile is big. The cheapest 180gr 10mm ammo shoots over 1,100 fps. The shorty Glock 29SF slows things down by about 100-200 fps depending on ammo. It also holds 17+1 using a Glock 20 mag with +2 extension. Don’t compare 10mm to .40 S&W. Compare it to a .357 mag, but the 10mm carries 3 time the ammo. Ammo cost is similar to .357 mag also.

  5. Doubletap ammo loads .40 S&W with 200 grain bullets @ 1050 FPS for 490 ft.lbs. muzzle energy. I’ve never used anything over 180 grain in my 40 myself though.

  6. Attn:Steve Camp. I do not know where you are getting your info, but it is wrong. The 10mm Auto and the 40 S&W are both a .400 diameter bullet and the 10mm case is .142″ longer than the 40S&W. .992 vs .850. The overall length is also about .142″ longer,depending on the grain bullet you are using. The 10mm Auto uses a large pistol primer and the 40S&W uses a small pistol primer. The 10mm Auto can propel a 200 gr. bullet over 1200/ft.sec. You can’t even load a 40S&W with a 200 gr. bullet,It isn’t safe. I have a S&W 411, Glock 22 and 23 in 40S&W and a Colt Delta Elite and a Glock 20 in 10mm Auto. The felt recoil is noticeably different. I hope this info was helpful.

  7. I am not sure I understand why the 10mm is touted as a better round than the .40S&W
    The .40S&W is .007 bigger than the 10mm. They are similarly shaped. I would think they would be an equal for each other. I mean 7 thousands of an inch is nothing. To put this in perspective… That is less than 2 pieces of paper put together. Now the only thing I can figure is maybe the 10mm has more grains of powder? maybe!! Well if someone could explain why the 10mm is on Steroids compared to the .40S&W I would appreciate it.

    Thanks Guys

  8. Rokurota,
    I am 5’7″ as well and carried a .357 Magnum for many years as a duty weapon. So I am in agreement with you in that we “runts” can shoot the big stuff, and do. However, this was the finding of the FBI and their conclusions which were based on hundreds of candidates not just two bulldogs like you and me.

  9. Why is it always said that “females and small-statured” folks can’t handle the big rounds? Those two aspects have little to do with pistol handling. I am 5’7″ and I love shooting .45s, .40s and .357s. Took a female friend shooting for the first time and she didn’t flinch at all emptying my .357 at paper. On the other hand, a “large-statured male” friend refused to shoot my G19 after a few rounds and stuck with the .22.

    It may be that in the FBI trials, it was the women and smaller folks that had trouble, but don’t tell me women and runts like me are universally recoil-shy. It varies by shooter.

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