At the turn of the 20th Century people really liked small defensive pistols, and people always like the ‘latest thing.’ The latest thing in pistols was the semi-automatic or self-loading pistol, and John Moses Browning knew an opportunity when he saw it; there would definitely be a market for a tiny pistol.

A small gun needs a small cartridge, and the smallest available was the .22 Rimfire, but this was problematic for a variety of reasons; the rim made stacking them in a magazine a challenge, they weren’t completely reliable and the soft lead bullets did not lend themselves well to semi-automatic pistols. Eventually most of these issues were resolved, but there at the beginning Browning went a different way; he designed a new cartridge.

.25 Caliber was as small as he could make it and still use a standard small pistol primer. He made the bullet 50gr. to match the sectional density of the 40gr. .22, and gave it a copper jacket to better survive cycling in a semi-auto pistol. Reducing the size of the rim made them easier to stack in a magazine but still allowed the cartridge to headspace properly, and the groove in front of it allowed the extractor to grab the case. It was loaded to mimic the performance of the .22 Long Rifle from a short barrel, which it does quite well. The new cartridge was called 6.35mm Browning, or in America the .25 Automatic Colt Pistol (ACP.)

Browning designed a tiny pistol around this new cartridge, and it was introduced by Fabrique National of Belgium as the Model 1905, and by Colt in America as the Model 1908 Pocket.

While the cartridge is certainly marginal as a self-defense round the small size and ease of concealment made these guns very popular, and other manufacturers quickly followed suit. Interestingly their efforts were not restricted to micro-pocket pistols. While the Mauser Model 1910 is certainly a petite gun, it is nowhere near as small as the Colt, and at one time the Walther PPK was offered in this chambering. Before WW1 Belgian manufacturers even offered small Velo-Dog style revolvers in this cartridge.

Some Rapid Fire competition pistols were produced in .25 Auto, and after WW2 the Lerker company in Italy even produced a machine-pistol. The tiny cartridge allowed twenty rounds to be carried in a standard-size pistol grip, and the diminutive cartridge produced so little recoil that the gun was reasonably controllable in full-auto fire. These guns attracted little interest, and only 150 or so were made.

The European gun-making community produced a plethora of micro-pistols chambered for this cartridge, often of wildly varying quality. Such guns remained popular for many decades, and many police officers carried one as a back-up to their service revolver. The .25 ACP reigned as king of the vest-pocket guns until the 1960’s. It’s heyday ended with the Gun Control Act of 1968 which, under the mistaken belief that criminals preferred small, concealable guns to large intimidating ones, banned the import of these tiny pistols. As the US was far and away the biggest market for these guns this had major ramifications for manufacturers, some of whom folded.

Some manufacturer’s like Colt continued to import these guns as ‘kits,’ which when assembled in the US were still quite legal. Others began producing guns in the US, most of which were inexpensive and not of high quality. The Raven P25 for example, retailed for around $40 in the 1980s, and was made largely from cast zinc alloy. Similarly constructed guns were made by Davis, Jennings and a host of others, and these simple, cheaply-made guns account for nearly all domestic production in this caliber today.

In the end the cartridge was relegated to irrelevance not by it’s lack of power, but by misguided legislation. That being said, by the 1970s it was not well-regarded by the ‘gun community.’ Colonel Jeff Cooper, one of the founders of modern ‘combat pistol’ competition and theory, is often quoted as saying, “Carry a 25 if it makes you feel good, but do not ever load it. If you load it you may shoot it. If you shoot it you may hit somebody, and if you hit somebody, and he finds out about it, he may be very angry with you.”

I suppose even Colonel Cooper could say stupid stuff. A lot of people have been killed by a .25 ACP, but there are many anecdotes about .25 ACP failing to stop people. Recent study of actual shootings show that it works surprisingly often- far more often, in fact, than it fails. A lot of this can be attributed to the FIBS effect; ‘F*ck, I’ve Been Shot!’ In point of fact nobody likes to take a bullet, any bullet, and often it triggers a flight response. As a civilian having an attacker run away amounts to ‘stopping’ them. They have ceased to be an immediate threat of death or grave bodily harm, and that’s the goal.

Still, there are few that would argue that a cartridge designed to replicate the performance of .22 LR (from a short barrel) is a potent man-stopper. With good shot placement it can work, but it is far from a good choice if there is any reasonable option. These days .25 Auto pistols are generally purchased as a curiosity, or in the case of the cheap cast-alloy guns, by people that simply cannot afford something better.

Today the role formerly filled by micro-pistols chambered in .25 ACP is most often filled by tiny single-action revolvers offered by North American Arms, mostly in .22 LR or .22 Magnum; they’re the gun you carry when you can’t carry a gun, or as a backup or even as a backup to a backup. Testing has not shown these to be notably more effective, and while they are more available than quality .25 Automatic pistols they are more difficult to shoot well or rapidly.

OK, So How Bad Is It?

It depends on your perspective. As a defensive round? Pretty bad. Compared to .22 LR out of similar guns? There’s not much to choose between them. For an objective standard we’ll turn to gel tests, which were conducted firing through four layers of denim into Clear Ballistics gel. Most loads were not chronographed as the batteries were run down and it needed recharging (oops.)

Fiocchi 50 gr. FMC-RN– 10-1/2″ of penetration. Bullet tumbled and wound up base-first.

Sellior & Bellot 50gr. FMC-RN– 11″ of penetration, Bullet tumbled and wound up base-first.

Fair to say that if more shots were tested these two rounds would likely come out about even in penetration.

There are a number of 35gr hollow-point loads also on the market, and I have seen this test performed with them. They tend not to expand and penetrate slightly less. There was a load I tested in the mouse-gun test that did better-   a 58gr. hard-cast flat point over 1.1gr. of Red Dot with a CCI 300 small pistol primer. The gave a velocity of 646 fps., 54 ft./lbs of energy and 12-1/2″ of penetration. This load also tumbled and ended base-first. Yes, I actually re-load .25 ACP. I would also like to note that the power of this round could be increased and remain within safe limits.

These results pretty much mimic .22 LR from the tiny NAA revolvers, and aren’t significantly worse than .22 Magnum from these guns.

Gel does not tell the whole story, of course; there are accounts for all of these tiny calibers being deflected by a skull or ribs, or even deflected around the rib-cage while remaining under the skin. There have been cases of spectacular failures of these rounds, and cases where someone took a single hit and dropped like a pole-axed steer. At this power level odd things happen, and bullet performance can be whimsical. Shot placement, of course, is always crucial, and with small, low-powered rounds it is even more so.

In the end it’s the same as any of these genuinely tiny guns; it’s better than harsh words, certainly, but it’s not a good choice if a better option is practical and available.

Is it Obsolete?

Again, it depends. Sometimes, for some people, circumstances dictate that a tiny gun may be their only option. They are also very easy and convenient to carry, so it’s more likely to be available if you need it. That there is still a market for tiny guns- NAA makes both their small revolvers and super-compact semi-autos, and people are buying them. I view these as the gun of last resort, to be used when conditions are such that a larger gun is simply not available. I tend to have my Seecamp LWS32 on my person at all times, simply because it’s so easy; it’s the gun I carry when I am not carrying a gun.

There is still a thriving business done in micro-guns, so it seems they do still have a mission. If you accept the mission, you accept the caliber. While high-quality modern .25s are a bit thin on the ground they are out there, as well as a plethora of older guns from the like of Colt, Beretta and FN, and inexpensive but functional guns are still abundant as well. Ammunition is still in production and widely available, and ammunition companies are still engaged in trying to develop more effective loads for them.

Another facet is in custom guns. During the last shortage of .22 LR some people had revolvers converted to fire .25 ACP as a re-loadable alternative to rimfire cartridges, and unsurprisingly it works quite well in that role.

So, while it is accurate to say that .25 ACP is in it’s twilight years, I don’t think we can really say that it’s obsolete. Whatever our opinion of the effectiveness of these guns, people keep buying them. Fair to say it won’t be vanishing into obscurity any time soon.

Michael Tinker Pearce, 25 August 2020

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