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GUNS Magazine Digital April 2011 - Page 18
• J O H N B A R S N E S S • RIfLE CARtRIdGES IN HANdGUNS Why they perform so well may surprise you. friend has a favorite question he occasionally springs on unsuspecting shooters: “What cartridge do modern hunters considered short-ranged and inadequate in a rifle, but flat-shooting and powerful in a handgun?” The answer, of course, is the .30-30 Winchester. In the early days of the metallic cartridge many cartridges were used in both rifles and handguns, because most early cartridges were rimfires. Rimfires must use thin brass in order for the priming compound to go off; the reason they’re relatively low-powered and short. Soon, however, centerfire priming allowed the use of stouter cases, allowing higher pressures, and rifle and handgun cartridges soon evolved along very different paths. Due to the endlessly fickle and wondering nature of humanity, however, many shooters still like to shoot rifle cartridges in handguns. Some strange contraptions have been developed for the purpose, including huge revolvers chambered for the .45-70; but these days most handguns chambered for rifle rounds are longbarreled single-shots, either boltaction or break-action. That same friend calls such firearms “hand carbines,” but they’re a lot of fun to shoot. They’re typically very accurate, partly because they’re normally equipped with scopes and partly because shorter barrels are stiffer barrels. I once spent a day shooting prairie dogs with my friend Rod Herrett, the handgun stockmaker from Idaho. We used a pair of Rod’s bolt-action handguns in .223 and .22250 Remington, and when shooting over a rest (as most prairie dog shooters do) we hit prairie dogs consistently out to 300 or 400 yards. Rod killed one at around 600 yards. Most rifle shooters don’t do any better. The Thompson/Center Contender has probably done more for the sport of shooting rifle rounds in handguns than any other firearm. The .30-30 tRAJECtORy COMPARISON, RIfLE vS. HANdGUN 170-GRAIN ROUNdNOSE, 2,100 fPS (RIfLE) 100 yards 200 yards 300 yards 0 -9.4" -33.6" A 125-GRAIN SPItZER, 2,300 fPS (HANdGUN) 100 yards 200 yards 300 yards 0 -6.5" -23.2" Contender’s interchangeable barrels make experimentation easy, and allow the same action to be used as both a “real” carbine and a handgun. This versatility tempts many shooters who wouldn’t otherwise be interested into trying a rifle-cartridge handgun and handloading for their new toy. Peak Pressure The biggest misconception of new hand-carbine handloaders is that shorter barrels require faster powders. This is due to the common myth that smokeless powder continues to burn all the way out the muzzle of even longbarreled rifles. Instead, smokeless only continues to burn a short distance past peak pressure, and the peak occurs a short distance in front of the chamber. The muzzle flash we see in dim light isn’t caused by still-burning powder (another common myth), but by hot powder gases reigniting when they hit the oxygen-rich atmosphere. This doesn’t mean that unburned powder doesn’t get blown out the muzzle, but it’s no longer burning. Due to the extreme drop in pressure after the peak, the powder gas is no longer hot enough to ignite any unburned powder kernels. (Remember freshman chemistry? In thermodynamics, pressure and heat directly affect each other.) In fact, if the cartridge develops the pressure the powder was designed for, 99 percent of the powder is consumed not far after the pressure peak. The powder gases in any centerfire rifle round keep expanding throughout the barrel, even after all the powder that’s going to burn has burned. This is why longer barrels produce Handguns chambered for rifle cartridges are fun to shoot, though they often require different shooting techniques than conventional handguns. 18 WWW.GUNSMAGAZINE.COM • APRIL 2011