Folding or Compressible Stock
One disturbing feature of assault weapons is how easily they can be transported without attracting attention. Handguns, of course, enjoy this benefit by their very nature. They're designed to be small and easy to carry and conceal. Rifles, too, have evolved in this direction. It's hard to imagine anyone sneaking around with a rifle from the late 1800s or early 1900s. The Springfield Model 1855 rifle-musket stretched 56 inches (142 centimeters) from end to end, while the Lebel M1866, used by the French infantry in World War I, measured almost 51 inches (130 centimeters) long. Both weapons would have been difficult to conceal in the back of a car or beneath a coat.
Over time, however, rifles became shorter and lighter. They also introduced new concepts, such as folding or detachable stocks, to increase their flexibility. The AK-47 assault rifle came in several designs and configurations, each offering different advantages and capabilities. In his Pulitzer Prize-winning book "The Gun," C.J. Chivers describes the flexible nature of the famous Russian firearm: "The AK-47 was small. No mule was required here. While not a precision rifle, it was accurate enough for most shots a man might be expected to take. Its ammunition was lightweight. ... Its variant with a wooden stock could be hidden beneath a blanket. The variant with a folding stock could be slung inside a coat."
Modern rifles continue the tradition. The AR-15 platform enables owners to swap out components and make modifications. One popular change involves the rifle stock and replacing the factory version with a folding or compressible stock. The folding version allows someone to reduce the length of the weapon considerably, which makes it easier to transport or carry in close quarters. The latter makes it easy to accommodate the user's body type or equipment configuration. Many states consider both stock modifications to be military features and, as a result, illegal when combined with other characteristics.