Brass Fetcher Ballistic Testing

The 9x18mm Police cartridge was a joint venture between Dynamit Nobel and SIG developed in the mid 1960’s as a high-performance replacement for the 380 ACP handguns in police and military service at the time. It is not a modification of an existing cartridge but rather a blending of the 9mm Luger and the 9x18mm Ultra which was developed by the German Air Force during the Second World War.

While outwardly-similar in appearance to the 380 ACP, the case capacity of the 9x18mm Police is 5% greater and the cartridge case thickness is identical to the 9mm Luger which allows loads considerably hotter than the 380 ACP to safely be used. The situation is similar to the difference between 38 Special and 357 Magnum—the latter has a longer and thicker case than the former, which allows higher pressures and notably better terminal performance.

Readers with an interest in history will note that at the time of the 9x18mm Police development, Europe was under threat from the terrorist activity of groups such as the Red Army Faction and the Red Brigades. Correspondingly, police forces at the time wanted greater firepower from their handguns as they were facing a new threat: sudden, intense acts of violence in heavily populated areas. While my suggestion with firearm selection is to carry the gun that you can shoot accurately, it is also very important that you strive to improve your aim and to carry the next-largest firearm.

The 9mm Police cartridge fits this bill perfectly as it is as effective as a 38 Special snubnose but can still chamber in factory 380 ACP handguns with minimal or no modification. Often overlooked in our current societal context is the value of concealed carry for shifting the balance of the fight against your attacker. It is a fact that mass shooters prefer ‘victim disarmament zones’ such as schools and churches. Anyone cowardly enough to perpetuate a civilian massacre is not going to be willing to stand and fight, as a righteous defensive shooter is willing and prepared to do. I recommend 380 ACP mouseguns as a minimum to experienced pistol shooters but the 9mm Police cartridge allows these guns to move to the next level of terminal performance. Single-stack handguns chambered for 9mm Luger are no more ‘pocket guns’ than is a 38 Special snubnose—they are simply too large to be drawn reliably from a pocket. The absolute maximum frame size for this task is the 380 ACP/9mm Police handgun.

Let’s take a look at the handguns that are already available for this cartridge and those that I’ve found can easily be customized:


WeightT: 28 ounces

Widht: 1.4 inches

Barrel Lenght: 3.9 inches

Overall Lenght: 6.9 inches

Height: 4.9

Magazine: 7 rounds


WeightT: 10 ounces

Widht: 0.75 inches

Barrel Lenght: 2.5 inches

Overall Lenght: 4.9 inches

Height: 3.9 inches

Magazine: 6 rounds

SIG P238

WeightT: 15.2 ounces

Widht: 1.1 inches

Barrel Lenght: 2.7 inches

Overall Lenght: 5.5 inches

Height: 3.9 inches

Magazine: 6 rounds

While it is preferable to obtain a factory original firearm chambered for the cartridge, this remains an experimental concept to date with limited supplies of factory firearms and ammunition available. If enough demand is created for this cartridge, as has occurred in the past for the 32 NAA, manufacturers of ammunition and small concealable firearms will step up and serve the market demand. What follows is a written summary of the R&D work that I have done, in the interest of aiding the manufacturer(s) decision to pursue the marketing of 9mm Police pocketguns.

Experimentation with the Kahr P380 and the SIG P238 (both originally 380 ACP firearms) has shown that both guns are readily convertible to fire 9mm Police ammunition. Figure 1 shows the general cartridge drawings for the different “ 9mm(s) ” to illustrate the dimensional differences we are discussing.

What’s great about the similarity between the 9mm Luger and 9mm Police cartridge case taper is that you can use a standard 9mm Luger chamber reamer to make the 9mm Police chamber : simply set your lathe to run in 18.00mm (0.709”) as opposed to the normal 19.15mm (0.754”) for the Luger. This is good enough for test and evaluation though more careful analysis will reveal that the outside diameter of this new case neck will measure 9.67mm as opposed to the called-for 9.68mm neck diameter.

Although the chamber dimensions are critical, there are many other areas of importance that must be considered when evaluating whether a particular 380 ACP is a good fit for conversion (whether at the shop or the factory.) Primary among them are the magazine length, barrel feedramp and the clearance under the extractor claw. Many 380 ACP handguns were tried for this project and the two that had magazines long enough to function with the longer cartridge were the Kahr P380 and the SIG P238. To check, simply load 7 380 ACP cartridges with a cartridge overall length of 1.000” and load them in the prospect magazine. If they all move up easily when you push the cartridges out with your thumb, the next step will be to load them in the gun and begin to hand-cycle the slide.

Naturally, this step is to check to see if the rounds will slide easily under the extractor and that the geometry of the feedramp is generous enough to allow loading into the weapon. There are two manufactures of ammunition available currently— Fiocchi and Hirtenberg. Prior to the ammo shortage beginning in late 2012, Fiocchi listed their excellent 100gr FMJTC as a currently-produced item though actual availability in the United States market may be somewhat more limited. It is conceivable that 9mm Luger cases could have the rims individually turned down and then the cases resized in a 9mm Police resizing die.

This should be reserved as one of your last options because of the inordinately large effort of time and money required to do this. It’s much easier to call or email your favorite pocketgun manufacturer and tell them what you would like to see for sale at your gun dealer.

Bullet Exiting barrel

0.00000 seconds into firing

New Cartridge Engaging feedramp

0.01370 seconds into firing

The cartridge hung up on the bottom of the extractor claw because of the longer length. This was partially remedied by using the Fiocchi brand ammunition in this gun because the rear of the rim is beveled to prevent this occurrence. Polishing the bottom of the extractor and removal of material are also viable options if you wish to modify your own firearm. Here is the time-displacement curve for the above event, where we look at the velocity of the slide as a function of distance traveled from its start point at the time of trigger pull:

Notice the velocity of the slide on the top part of the graph nosedive around the –0.7 inch mark. We really want a smoother curve here, especially if the weapon has been fouled from repeated firing. The good news is that the dimensions of the 9mm Police is much closer to the 380 ACP than the Luger and smaller guns already are made for the Luger—it wouldn’t take more than a few drawing changes to produce an entirely new mousegun caliber with much greater effectiveness.

These figures are based on maximum pressure loads using a 90gr JHP bullet. Please note that the Smith and Wesson 642 had a 1.875” barrel length but the cartridge length for a 38 Special case is 1.155”, which gives us an effective barrel length of 3.0” for this weapon. From the graph, it is apparent that a 9mm Police from a 2.75” barrel is the ballistic twin of a 38 Special +P snubnose. The superiority of both calibers is apparent when compared to the 380 ACP.

While it is possible to chamber a 9mm Luger cartridge in a small pocket-size handgun, rare is the shooter who can effectively control such a gun. This statement will likely generate some emails from the chest-thumpers who will tell me that they are “plenty accurate” with their 9mm mousegun. I had the great fortune to complete the Gunsite 250 Defensive Pistol class in 2003. That’s five days of professional handgun training from some of the best in the world. When I got to shoot a Rohrbaugh R9, itself smaller than a SIG P238, I liked the gun a lot. But what I can say is that shooting it in a realistic timed qualification course like that the FBI uses would be challenging indeed! From the perspective of stopping an attacker, the balance that needs to be struck when choosing a cartridge for defensive use is that of terminal effectiveness versus recoil. It’s been said many times that a hit with a 22lr is better than a miss with a 357 Magnum. The common thought is that an attacker will run away the moment that you pull the gun out on him. This might be true for the majority of criminals today .. But what about the criminal threat in the near-future? Violent crime and property crimes have continued to increase notionally in the US with the breakdown of the manufacturing base and traditional family structures. People who would have otherwise been “law abiding” are now the second generation product of a broken family and have no economic incentive to ’do the right thing’ as existed in the past. If you didn’t want to go to college, you could earn a respectable living in a trade or laboring in a factory… now those factories are rusting and in a state of decline. Evidence is emerging of a linkage between usage of prescribed psychotropic medication and psychopathic breaks with reality. All opinions about drug use aside, a person who is heavily under the influence of drugs has the potential to become a fully motivated fighter.

While normally encountered on the battlefield, we are all aware of anecdotal stories of the woman lifting the car off of her trapped child using nothing but the strength-enhancing effects of adrenaline. This event is well within the realm of reason as the physiological effects of an actual threat or a hallucinated one are exactly the same and have been demonstrated repeatedly throughout the literature. What this means to us is that such an adversary will not stop their attack unless you physically disable or kill them.

The second side of the coin, and perhaps the most worrisome, is the economy. A hungry person is a fully motivated fighter. Horror stories from the Weimer Republic and the starvation that happened in pre-WWII Germany will help to illustrate my point. It is prudent when discussing the use of deadly force to defend yourself, to look at the reasonable worst-case scenarios. What we might be faced with in the future are smart and mostly rational people who think and look like you. The only difference is they might have failed to prepare for shortages and now see you as the only thing between them and what they want. This is why I hold mouseguns to the same standard as larger handguns—you don’t know where you will be and what you will be armed with if you ever need that gun. In my case, I carry in my pocket most of the time and from the distinct lack of the appearance of people carrying larger pistols OWB/IWB where I have lived ... I would say that pocket carry is what most people use, most of the time.

Mouseguns typically only carry 6 cartridges in the magazine. This is why you must hit the targets in a vital spot and hit them with everything that you have. Let’s take a look now at the terminal ballistics of the 9mm Police.

More Info


10-percent Ballistic Gelatin Shot

See how well this caliber stacks up against the FBI performance requirement of expansion and 12.0” or deeper penetration depth.


20-percent Ballistic Gelatin Shot

See how well this caliber stacks up in military-standard performance evaluations.


Heavy Clothing

Heavy Clothing is placed in front of the gelatin block to simulate an attacker wearing winter clothing.


Car Door

FBI Standard test fixture simulating a target using the thinnest part of a car door for cover.


Car Windshield

FBI Standard test fixture that addresses bullet performance if you have to fire through a windshield to hit the target.


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9x18mm Police

Reloading Table


9x18mm Police

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