January 30, 2013

Bottleneck Cartridges

Bottleneck pistol cartridges are nothing new. The .30 Luger (7.65x21mm)…

Richard Mann

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CH Feb FN FiveSeven Ammo
FN’s Five-seveN pistol was built specifically for the 5.7x28mm cartridge, a bottleneck design that helps lightweight projectiles fly at approximately 1,800 feet per second.

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BNPC_001_phatchfinal
Bottleneck pistol cartridges can feed even more reliably than straight-walled pistol cartridges, and they can drive bullets at higher velocities. From left: 5.7x28mm, .25 NAA, .32 NAA, .357 SIG and .400 CorBon.

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BNPC_002_phatchfinal
The 5.7x28mm cartridge—available from FN, Fiochi and Federal—can drive a bullet at almost twice the speed of sound with very little recoil.

Bottleneck pistol cartridges are nothing new. The .30 Luger (7.65x21mm) was introduced in 1900 by Deutshe Waffen u. Munitions Fabriken in Germany for the Luger automatic pistol. The .30 Mauser predates the .30 Luger by seven years. Most pistol cartridges utilize what is known as a straight-walled cartridge case—a case without a shoulder. A bottleneck pistol cartridge has a shoulder like a modern rifle cartridge. Bottleneck pistol cartridges are frankly not that well known with a lot of handgun enthusiasts. The most successful of the lot is the .357 SIG, which has seen some adoption by law enforcement agencies. Its appeal to cops is that it offers near .357 Magnum performance from a lighter, smaller, higher-capacity semi-automatic handgun. The .357 SIG is based on the .40 S&W cartridge case but loaded to a higher pressure—14 percent higher to be exact. As you might expect from duty-handgun-sized pistols, the muzzle blast from a .357 SIG is pretty significant.

More Designs

An interesting bottleneck pistol cartridge is the .25 North American Arms (.25 NAA). It was developed by Kentucky firearms writer J.B. Wood and is based on the .32 ACP cartridge case. Wood’s goal was to increase the expansion of .25-caliber bullets when fired from short-barreled handguns by increasing velocity. By using the larger .32 ACP case, Wood was able to get more powder behind the .25-caliber bullet than is possible in a .25 ACP case, and the result was indeed higher velocity. And, more velocity means more expansion after impact. The .25 NAA also proved to feed reliably, which is a trait common with many bottleneck pistol cartridges. North American Arms offers its compact Guardian pistol in this chambering.

North American Arms also offers the same pistol chambered for another bottleneck pistol cartridge: the .32 NAA. Development of this cartridge was a joint effort between North American Arms and former police officer/gunwriter Ed Sanow. It uses a .380 ACP cartridge case that’s necked down to .32 (.312) caliber. I’ve had a good deal of experience with this cartridge and actually own and sometimes carry a pistol so chambered. It is capable of driving a 60-grain, wide-expanding bullet to a depth of 7 inches in 10 percent ordnance gelatin.