Tuesday - January 10, 2012
Building A Better Mousegun
A “mousegun” is a very tiny pistol, made to fit in your pocket. Usually they are chambered for the diminutive calibers; .22LR, .25 ACP, and .32 ACP. Lately several have come on the market that use the .380 ACP. None of these cartridges is a powerhouse, but when the foo hits the shan they are better than no gun at all. First rule of gun fighting: bring a gun.
It used to be that semi-automatic pocket pistols all used a blow-back action, like the Beretta Tomcat. A blow-back action is one without any kind of breech locking mechanism; the action is held closed by spring power alone, and held somewhat closed during firing by the mass of the pistol’s slide. Although such guns are easy and inexpensive to make, this kind of design is limited to cartridges that generate very low chamber pressure, and in a stubby little mousegun that always means low velocity. And low velocity means low muzzle energy, which is another way of saying they don’t have much killing power, and they certainly don’t have much of any stopping power.
(Huh? Killing power is just that. If you shoot something in the vital organs with a bullet that can penetrate deep enough to puncture those organs, and can dig a hole at least half an inch wide while doing so, the critter you have shot is going to die. Eventually. Doesn’t matter if it’s a squirrel or an elephant, although the required penetration depth varies with the size of the critter. Stopping power is the ability of a bullet to shatter, destroy, and permanently displace internal organs and nerve pathways enough so that the creature stops in its tracks, stunned. It stops running, stops attacking, and hopefully falls over. Stopping power is more of a concept based on observations, and is often given the colorful label “hydrostatic shock”. All animals are essentially bags of water. Smack the bag hard enough and it bursts, or at least gets pushed out of shape. Put a big enough hole in it and it quickly leaks out. And that’s the “science” of killing things, without going into too much graphic detail ... look up “wounding theory”, “terminal ballistics”, “temporary vs permanent wound channel” if you want to know more.)
With nearly the entire USA now being allowed by the States to exercise their God given right of self-protection, a vast number of people have taken to carrying a pistol on their person. “CCW” we call that. While some folks prefer and would argue for “open carry” (ie a pistol in a holster on your belt) most of us would prefer to not advertise the fact, and elect to carry a pistol in our pockets, or somewhere out of sight. The problem is that a pistol small enough to drop in your pocket and light enough to carry around without pulling your pants down is almost always chambered for one of the earlier mentioned puny cartridges.
Things have changed, somewhat. In the past few years there have been a plethora of very tiny locked breech .380 ACP pocket pistols brought to the market. So many that .380 ammo was darn hard to find for a couple years recently. For semi-auto mouseguns the .380 is about the best choice you have; while the 9mm Luger (aka the 9x19, 9mm Parabellum, or just the 9mm) is a far more powerful cartridge, it has not been available in any very tiny pistol at all, ever. Ok, you can get a 9mm from Boberg these days for a bit over $1000. And there’s that one from Rohrbaugh or however you spell it, also over $1000. And both of those pistols weigh more than 3/4 of a pound and are nearly an inch thick. Small, but heavy for their size and a bit thick to go in your pocket without leaving a big old bulge. But most other 9mm pistols are quite a bit bigger although they usually cost a lot less.
The current generation of lightweight .380 pocket pistols are all about 5” long, 3.6” tall, 3/4” thick and weigh in around half a pound. That’s pretty tiny and pretty light. And most of them (Ruger LCP, Kel-Tec P3AT, the Taurus model) cost $350 or less. And they all have locked breech designs these days, which makes for a much stronger and safer pistol.
The problem is still with the .380 ACP cartridge. And with the lawyers. And with SAAMI, the industry firearms governing board. And to point it all out, I have to build a table or two. Damn.
| Cartridge | bullet dia. | case base dia. | case mouth dia. | wall thickness | case length | overall length | SAAMI max pressure, PSI |
| .380 ACP | 0.355” | 0.374” | 0.373” | 0.009” | 0.680” | 0.984” | 21,500 |
| .38 Auto | 0.356” | 0.384” | 0.384” | 0.014” | 0.900” | 1.28” | 26,500 |
| .38 Super | 0.356” | 0.384” | 0.384” | 0.014” | 0.900” | 1.28” | 36,500 |
| 9mm Ultra (9x18) | 0.355” | 0.389” | 0.381” | 0.013” | 0.709” | 1.004” | 26,100 |
| .9mm Luger (9x19) | 0.355” | 0.391” | 0.380” | 0.0125” | 0.754” | 1.169” | 35,000 |
| .9mm NATO (9x19) | 0.355” | 0.391” | 0.380” | 0.0125” | 0.754” | 1.169” | 38,500 |
| 9x23 Winchester | 0.356” | 0.392” | 0.381” | 0.0125” | 0.90” | 1.3” | 44,000 |
| .38 Special | 0.359” | 0.379” | 0.379” | 0.010” | 1.155” | 1.55” | 17,000 |
| .357 Magnum | 0.359” | 0.379” | 0.379” | 0.010” | 1.29” | 1.59” | 35,000 |
Ok, several things pop right out here. The .38 Special and the .357 Magnum are revolver cartridges. Not only do the cases have rims, their OALs (overall lengths) are a bit big to fit inside the handle of a semi-automatic and fit comfortably in your hand. It’s been done, but those guns don’t fit everyone. For all extents and purposes, all the cartridges listed here use 9mm bullets. The revolver cartridges are speced for lead bullets, so they are a tad oversize. The .38 Auto and the .38 Super Auto date back to John Browning’s day, and are the exact same cartridge but loaded to two very different pressure points. Which can lead to disaster if you put the wrong ammo in the wrong gun. Oops. A difference in spec of 2 or 3 one thousands of an inch is meaningless, given production tolerances. So a .389” case diameter is really the same as a .391” case diameter, although a .355” diameter bullet is not the same as a .356”, .357”, or .358” one. But they’re all 38s ... or 9s ... that’s just how guns are: confusing.
But you can easily see that the .380 Auto is a much smaller case made with thinner (weaker) walls and set to a much lower pressure standard than the 9x19, whether we’re talking Luger or NATO. Yes, the Army made the Luger a far more effective round by jacking the pressure up 10%. Almost all 9mm pistols can handle it, but to be safe I’d look for one specifically chambered for the 9mm NATO, like the Beretta 92F, which is the pistol the Army uses. For now.
The 9x23 Winchester is to the 9mm Luger what the .357 Magnum is to the .38 Special: it’s the same case, just longer, and set to run at a much higher pressure. This is a specialty cartridge used mostly by metallic target shooters, but I put it in to show that pistol cases in this size range with 0.0125” thick walls can handle quite a bit more pressure than even the 9mm NATO. The .357 Maximum (not listed here) is similar; it’s just a stretched .357 Magnum and it also runs at 44,000 psi. Which is the same pressure bracket used by the .30-30 rifle (43,500 psi); rather hot for a handgun, but not impossible.
So the Gun Nutz argue that the .380 ACP isn’t enough gun, the modern 9x19 is, but the .357 Magnum is usually too much gun. Go figure. But what they are talking about is stopping power and killing power, and those two are inextricably linked to bullet weight and velocity. More equals better, but too much is too much. Especially in a dinky little half pound pistol the size of the palm of your hand that you can only hold on to with 3 fingers, 1 of which is pulling the trigger.
How do the lawyers come in to play here? Because SAAMI, the regulating group, sets the cartridge pressure standards as a Maximum Probable Lot Mean, or MPLM, and that means that no cartridge that meets their spec (and they all have to) can ever exceed the maximum allowable pressure. Translated into lawyereese, that means all commercially available “factory ammo” not labeled as being designed to be over standard pressures actually runs a bit less than maximum pressure. Sometimes a lot less, and the trend is that the older the cartridge is, the lower the maximum becomes. And most of these cartridges have already been around for about 100 years. This is why folks load their own ammo, see? And why ammo brought in from Europe is so “hot”. No, it just isn’t as watered down lawyered up.
So is there a solution? Yes! But then again, no! That’s guns, and they’re confusing!!
Many pistol cartridges have an unofficial variant, a hot rodded version called a “+P”. There is no exact specification for what “+P” means, or furthermore what “+P+” means, but both of them mean “somewhat more than SAAMI pressure”. Or in lawyereese, “actually runs at SAAMI pressure”. Probably. And all the +P types of ammo should only be used in modern guns so chambered, of which almost none are. Or else it’s all on your head, m’kay? So there is a .38 Special +P, a quarter of the way between regular .38 Special and .357 Magnum pressures, and there are actually revolvers sold marked as such, because the original .38 Special runs at such anemic pressure that even a cheap pistol is more than strong enough for it. Remember that the Special started life back in black powder days, before the advent of chrome or moly steel. So any old crap steel these days is strong enough, and almost all the gun companies build them with really first class steel anyway, because they aren’t completely stupid. And while no +P designation exists for the .45 Colt or the .45-70, the loading manuals are full of “Ruger only” loads for them that are +P level or more, because that gun company builds really strong guns. But you may have trouble finding almost any other gun labeled as being chambered for a “+P” anything. (Confused yet? No? Good. Because almost every single rifle made for the .257 Roberts cartridge in the past 50 years has been labeled as a .257 Roberts +P. With guns, there’s always, always an exception or two.)
Of the 3 latest generation .380 ACP pocket pistols on the market, 2 specifically tell you not to use +P ammo. 1 of those guns will break if you do so. Maybe. The 3rd company says you can use the +P stuff, but not all the time. Because it will wear your gun out, and quickly. Why? Because super tiny lightweight pistols are engineered more towards the minimum than the maximum. They have to shave every last possible gram, and that means their parts are smaller, lighter, and thinner than those of bigger pistols. Therefore not as overly excessively robust. So the lawyers get involved ... and you know how that song and dance goes.
Right. So standard .380 ACP ammo is better than nothing, but not really quite enough. And .380 +P is a lot better, though still on the low powered side. Full powered 9x19 ammo is enough (and may over-penetrate), and even lame-o factory .357 Magnum ammo is far too much. For personal defense, we’re talking. Which means shooting people at close ranges who are trying to kill you. Let’s look at what the numbers are, and try and hack out that “just right” Goldilocks solution before the apocalypse gets here, m’kay Drew?
| Cartridge | Bullet Weight, grains | Sectional Density | fps Velocity, 2.75” barrel | Muzzle Energy, lb/ft |
| .380 Auto | 95 | 0.108 | 1000 | 200 |
| .380 Auto +P | 100 | 0.113 | 1060 | 250 |
| 9x19 | 124 | 0.140 | 1180 | 384 |
| .357 Magnum | 125 | 0.141 | 1300 | 470 |
| 9x18 Ultra | 100 | 0.113 | 1065 | 252 |
| 9x18 Ultra +P | 115 | 0.130 | 1150 | 346 |
I’m kind of giving away the surprise. The solution is the 9x18, and the better solution is the 9x18 +P. Which doesn’t yet exist except in my ballistics software calculations. But my numbers are realistic, and I can even tell you what bullet and what powder to use. The 9x18 has quite a number of names, but 9x18 Ultra is one of the more common ones.
The 9x18 is not new. It was developed in the late 1930s as being the most potent 9mm cartridge that could function in a cheap blow-back action. It is a big enough cartridge to seat a decent weight bullet with good sectional density; that means the bullet has enough mass to penetrate well and enough body so that it can expand enough without turning itself inside out. The OAL of the cartridge is small enough so that the thickness and width of a pocket pistol’s grips will still be fairly small and fit just about all hands. In its normal pressure form it packs as much energy as the iffy +P .380 ammo, and in its own +P form (36,000 psi) it has almost as much wallop as the modern 9x19 NATO, using a slightly light bullet for a bit less recoil. It’s the best middle of the road, and is just about completely unknown in the USA. It’s a European cartridge, and for a little while was what the euro-cops carried. These days they’ve all “up gunned” and carry the 9x19. So, where did this little wonder come from? It was designed back in the day by those wonderful leaders in science and technology of their age ... the Nazis. Oops.
Today’s generation of micro pocket guns, all of which have locked breeches, could easy be made to chamber the 9x18 +P. It would take an extra ounce of steel, perhaps two, and perhaps an extra tenth of an inch of length. But it could be done, and they’d be strong enough and then some. The lawyers and the marketing guys would have to get together though, and decide to make the case 0.002” longer and the OAL 0.005” longer and then give it a new name, probably something like “the all-new mid-size 9mm All American” and then never, ever breath a word about its history. Because nobody says the real “N” word, ever. Not that one. Sales killer, guaranteed. Even for certain insecticides which happen to be soooo so close to certain other poisons that have a vile and horrid history. And it would be just as bad with guns. Worse maybe. So don’t breath a word. Better yet, let Glock do it, and they’ll call the round the 9mm GAP ... especially since this one actually fills a gap, unlike their slightly silly .45 GAP cartridge from a couple years ago.
Posted by Drew458
on 01/10/2012 at 12:49 PM
Filed Under: • Guns and Gun Control •
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