Why a Pistol Caliber Carbine?

By Randy Wakeman

Ruger PC9 9x19mm Carbine
Ruger PC9 9x19mm Carbine. Illustration courtesy of Sturm, Ruger.

The notion of a carbine is attributed to the cavalry. It is shorter and lighter than a full length rifle, about the length of a curved sword or saber, that can be carried in a scabbard on horseback. Carbine length black powder rifles were consider low performance in terms of velocity and less accurate, due to the shorter sighting plane. The adoption of smokeless powder reduced this ballistic penalty.

The current Ruger PC9 and similar ultra-short carbines are a more accurate platform than a pistol. The shooter has more contact points, offering a more stable shooting platform than non-shoulder fired alternatives. There is less felt recoil, as the short barreled rifle has a stock weld to the shoulder and it is significantly heavier than a pistol.

For the regular shooter, pistol ammo is often cheaper than rifle cartridges. It should be, as it uses less propellant and brass.

As autoloading pistol cartridge propellants have fast burn rates, there is not as much velocity increase with a 9mm pistol cartridge carbine as there would be with a rifle cartridge, or even a magnum revolver cartridge carbine.

Ballistics by the Inch shows there often is little velocity gain. A Federal 115 grain JHP round achieves a muzzle velocity of 1188 fps out of a six inch barrel and 1295 fps out of a 16 inch barrel. This is still extremely slow for a carbine, for a .22 Winchester Magnum rimfire carbine with a 16 inch barrel shooting 45 grain Hornady FlexTip ammo hits 1702 fps.

9mm Luger (9x19mm) pistol cartridge bullets also have very poor ballistic coefficients. After all, 9mm is a .35 caliber round (.0355 inch diameter bullet), nearly the same diameter as the .357 Magnum (0.357 inch diameter bullet). The .357 fares much better out of a rifle, for a 125 grain Federal JHP round hits 2015 fps out of a 16 inch barrel. 2015 fps with a 125 grain bullet (.357 Magnum) versus 1295 fps from a 115 grain 9x19mm bullet is a huge difference.

For hunting medium game, Winchester ballistics credit their .357 Magnum 158 grain JHP and JSP bullets with a muzzle velocity of 1830 fps from a 20 inch carbine barrel. The remaining energy of these loads is 715 ft. lbs. at 100 yards.

As for the 10mm auto (.400 inch bullet diameter), velocities with Federal 180 grain Hydra-Shok ammo from a five inch barrel are 1069 fps and 1220 fps from a 16 inch barrel. A 240 grain Federal Hydra-Shok load from a .44 Remington Magnum (.429 inch bullet diameter) carbine nets 1619 fps from a 16 inch barrel, putting the 10mm to shame.

Now you know why 10mm carbines make little sense, compared to the 9mm variety. 10mm means more noise, less capacity, more recoil and a higher cost per shot. Perhaps this is why the FBI and the U.S. Military both have stuck with, or have gone back to, the 9x19mm.

Handgun cartridge performance in carbines, compared to rifle cartridges, is anything but amazing, except to say they are amazingly weak. The 9mm, 10mm and even the .357 Magnum is under powered compared to the .35 Remington rifle cartridge. The Hornady LEVER Revolution round for the latter drives a 200 grain bullet out of the muzzle at 2225 fps from a 24 inch barrel. Sighted-in three inches high at 100 yards, it is dead on at 200 yards, still hitting with 1315 ft. lbs. of energy at 200 yards. Don't kid yourself, no handgun caliber carbine is an ideal deer slayer.

One of the hits of 2018 is the new Ruger PC9 Carbine in 9x19mm. It is a handy, fun gun that is good for home defense, or plinking. It is a significant upgrade over the Hi-Point 995 genre of cheap 9mm semi-autos, not nearly as pricey as the Beretta CX4 Storm and it is a fraction of the price of the excellent Kriss Vector. Still, the 9mm Luger cartridge is no big game hunting round and no medium game hunting round, either.

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Copyright 2018 by Randy Wakeman. All rights reserved.