Picking your pistol determines your understating and capabilities. However, Your shooting environment and local laws delimit the pistol that suits you. Choosing the Best AR-15 Pistols for your self-defense and safety. How to build an AR-15 pistol depends on accuracy, ergonomics, and durability. An AR-15 pistol has a short barrel, does not have a stock, and is shorter than 26 inches overall. The absence of stock entitles the AR pistol to a pistol.