The Problem With PCCs Isn't The Concept, But The Government

(Note: This is a significantly updated version of a post I made several years ago). 

 

Pistol caliber carbines (PCCs) are the Rodney Dangerfield of firearms: they get no respect. The primary complaint seems to be that they are the size of the rifle, but lack the stopping power of a true rifle round. For instance, just a few days ago I had referenced an article, "Pistol vs Rifle Cartridges: There is a Difference" from Shoot On, which asked why you would use a pistol to stop a threat if you had a rifle available. Lucky Gunner has made the same point with regard to PCCs:

 

But if you’ve already decided to use a long gun, why would you get one chambered for the weaker cartridge of a pistol? Pistol caliber carbines are the worst of both worlds. They are feeble and anemic like pistols but carry the size penalty of a rifle. 

 

Back in 2017, when Nathanial F. still wrote for The Firearm Blog, he also argued that PCCs did not make any sense except as a range toy. And Warrior Poet Society released a video and article in 2022 going over the pros and cons of PCCs, and mostly finding cons. 

 

    When you look at these articles, the primary arguments against PCCs are that they don't solve a problem in a world filled with ARs because they lack the range, accuracy, ability to penetrate body armor, and terminal ballistics of a defensive rifle. (And, other than the body armor issues, you see the same arguments against using them for hunting unless you are simply going to use them for pest control).  

    What is being described in the article are the arguments on why submachine guns disappeared from military armories after the advent of small caliber select fire rifles in 5.56 (or 5.45 for the Soviets/Russians). But that such weapons are largely unneeded on the battlefield, even taking into account urban warfare, does not mean that they are unneeded or obsolete for the civilian at self-defense distances. In reality, the problem with the modern PCC for self protection isn't a result of anemic cartridges, but that government regulation has stuck us in an environment where the potential advantages have been outlawed and so we are instead stuck with pistol caliber weapons in a rifle body and with a rifle length barrel. 

    This isn't necessarily a detriment for all PCCs. Cartridges like the .357 Magnum, .44 Magnum, .45 Colt, etc., are in a whole different category from rimless pistol cartridges. If you look at the data collected from the Ballistics-By-The-Inch project, you will notice that these rimmed revolver cartridges not only benefit from longer barrels, but their velocities continue to show appreciable gains in velocity all of the way out to 18-inch barrels. For instance, a .357 Magnum load of Federal 125 gr. JHP has a gain in muzzle velocity of 932 fps between a 2 inch and 9 inch barrel. Going from 9 to 17 inch, we see a gain of 145 fps. And from 17 to 18 inches, we see another gain of 46 fps. I've seen other tests that have shown a .357 Magnum out of a 16-inch barrel is comparable to a .30 Carbine, and a .44 Magnum can be a good deer round out of a carbine. In short, then, I believe that the lever action pistol caliber carbines in .357 Magnum or .44 Magnum are practical.

    The same cannot be said for pistol cartridges intended for semi-auto pistols. Their velocities tend to plateau at the 8 to 10 inch mark and there is relatively little increase past that point. For instance, taking Federal 124 gr. Hydra-Shok JHP as an example, you will see a gain in velocity between 2 and 9 inches of 312 fps. From 9 to 11 inches, there is 0 gain in velocity. From 9 to 17 inches, there is only a gain of 38 fps. At 18 inches, the velocity drops 19 fps, erasing half of the gain from 9 to 17 inches! In fact, all but two Cor-Bon loads saw declines in velocity between 17 and 18 inch barrels. Federal 155 gr. Hydra-Shok JHP in .40 S&W shows a similar pattern. From 2 to 9 inches, you see an increase in muzzle velocity of 325 fps. From 9 inches to 17 inches, we see a gain of only 37 fps, and from 17 to 18 inches, we see only a 9 fps gain--most other loadings actually show a decline in muzzle velocity. 10 mm fares only a little better. Looking at the Federal 180 gr. Hydra-Shok load, we see a gain of 338 between 2 and 9 inches. From 9 to 17 inches, we see a gain of only 30 fps. From 17 to 18 inches, there is still a slight gain in this loading, 23 fps, but most of the other loadings show a decline in muzzle velocity. In short, the PCC firing a rimless cartridge like 9mm or .45 ACP will not show much increase in performance beyond an 8-inch barrel and so a 16-inch barrel is useless, or worse than useless because it adds unnecessary length and weight. 

 

    Conversely, with such short barrels, ballistics and reliability of the gas system become questionable with a 5.56 system. The Small Arms Defense Journal published a piece in 2023 entitled: "Barrel Length Studies in 5.56mm NATO Weapons" by Jason M. Wong. A couple points that are notable. First, he points out:

 

Short barreled gas operated weapons, of which the AR-15/M4 platform is of interest, pose increasing reliability errors with decreasing barrel length.  The prime reason is that as the barrel is shortened, there is decreased dwell time of the projectile in the bore after passing the gas port.  This makes timing more difficult, and adding muzzle accessories (such as a sound suppressor) will cause serious reliability issues, such as faster cycling. ...

Second, as to terminal ballistics, he explains: "To generate a lethal wound channel, the M855 projectile must have a velocity of at least 2,500 ft/sec on impact with the target.  Below that critical velocity, the M855 bullet simply drills a 1/4 inch hole in the target, which too frequently is not lethal unless it passes through a vital structure. ... The critical velocity of 2,500 ft/sec was in a barrel between 9 and 10 inches in length, which further shows the folly of considering a 7-inch barrel for this cartridge." In short, then, when talking about short barrelled weapons, you potentially lose the ballistic advantage offered by the rifle round; and probably much of the reliability as well, which brings us back to the PCC. 

 

    The real reason that we do not see more value from PCC weapons is because of government restrictions. Historically the PCC provided one or both of the following: 

1. It had a stock making it better for shooting at longer range, whether as a weapon built around a stock, or by being able to attach a stock to a pistol (and while such weapons probably did not see a lot of use in the West, that wasn't true in the wars in China in the early 20th Century due to Western embargoes on importing submachine guns).  
2. Allowed for automatic fire in a size smaller than a machine gun or select fire "battle rifle". And, with a stock attached, made such automatic fire fairly controllable at anti-personnel distances. In this respect, I am particularly thinking of the submachine gun. And in the latter regard, because they could make use of a simple blow back, open bolt mechanism, they could be made in a smaller form factor than most combat rifles, even assault rifles.

    Government regulation has consistently outlawed most of the characteristics that made PCCs valuable. The restrictions on short-barreled rifles essentially quashed any development of standard style pistols to which stocks could be affixed or production of short barrelled carbines (although the availability of pistol braces changed that situation somewhat). 

    Similarly, the passage of the National Firearms Act, which was intended to prevent civilians from being able to stand up to their government, has all but removed automatic weapons from civilian hands; and since no new weapons can be sold, it has effectively destroyed any development of new or better designs. While modern military doctrine largely eschews using automatic fire from combat rifles (essentially taking the "assault" out of "assault rifle"), in a civilian context, a small machine pistol or submachine gun would be a viable alternative to a shotgun, only shooting more effective projectiles than your standard 00 Buck. A point brought up by Timothy J. Mullin in his book, The Fighting Submachine Gun, Machine Pistol, and Shotgun.

    Finally, at the apogee of submachine gun and machine pistol development, manufacturers were able to develop some very small form factors such as we see with the Sterling submachine gun, or the Uzi submachine gun:

British Sterling Submachine Gun

This Dutch soldier appears to be using an Uzi or Mini-Uzi submachine gun.

But because of the prohibition on open-bolt designs, we typically see much larger weapons than is actually necessary for pistol caliber designs.

    Now I'm not saying that the answer is to go back to the Uzi or Sterling, or even open bolt designs. My point is that, but for anti-gun laws and regulations, we would have updated designs using more modern materials and capable of mounting optics and lights. And, in fact, with the development and popularity of pistol braces, we have started to see such developments. Hopefully, with some of the changes to enforcement of the NFA and a favorable judicial decision on forced-reset-triggers, we will see even more innovation. Because I do believe there is a legitimate argument for civilians having a stocked, light weight, short barreled, rapid-fire carbine shooting something with less recoil, flash, and sound than a rifle round or shotgun.