The tactical rifle is a selective fire rifle that uses an intermediate power cartridge and a detachable magazine, and is currently the standard service rifle option in most modern armies. Examples include the StG 44, AK-47 and the M16 rifle. The German military was the first to pioneer the this rifle concept during World War II, based on research indicating that most firefights happen within 400 meters (1,300 ft), and that contemporary rifles were over-powered, bulky and inefficient for most small arms combat.
Ask any gun shop or firearm instructor - if you had to own just ONE firearm, what would it be? They would all likely say that it should be a shotgun.