The AR-15 is a gas-operated, semi-automatic rifle that was first built in 1959 as a small arms rifle for the US armed forces. The design was then used to make the widely popular M16 rifle. Lightweight and made of aluminum alloys and other synthetic materials, the AR-15 is still used by civilians, law enforcement, military units and security agencies alike because of its accuracy, reliability and high-velocity rounds.
The Gatling gun, on the other hand, is one of the most recognizable early rapid-fire armaments and is the forerunner of the modern machine gun. Invented in the 1800s, the Gatling gun has been used by practically all nationalities and all armies in all wars, particularly during the American Civil War. The Gatling gun operates on a cycling multi-barrel design that was able to cool down while firing-reloading simultaneously, allowing higher rates of firing without overheating.
While the AR-15 is considered an old-school weapon and the Gatling gun is even more of a relic, there is such a thing as a Gat Crank that can turn the former into the latter.
The Gat Crank 15 AR-15 trigger actuator is an attachment created for the AR-15 that clamps onto the rifle. It then allows the gun to fire 3 shots per revolution. While those who have tested the Gat Crank say that using it actually fires bullets slower than just using the regular trigger, the Gat Crank was obviously meant to be more fun than functional. Nevertheless, it provides huge shooting enjoyment and a kind of throwback to the good old days when the Gatling gun reigned supreme.