The 9mm Lugar, .223 Remington and .45 Automatic Colt Pistol are the most popular ammunition calibers in the United States, according to prominent ammunition retailer Lucky Gunner. Lucky Gunner made this estimate based on their nationwide ammunition sales in 2013.
The 9mm ammunition is commonly used in pistols and submachine guns, such as the Heckler and Koch MP5. The .223 Remington ammunition is popular with sporting rifles, and the .45 ACP is commonly used in self-defense pistols.
Together, these three calibers represented more than 40 percent of all ammunition revenue at Lucky Gunner.
The most common gun in the United States, the AR-15 and its variants, can fire .223 Remington rounds or 5.56×45mm NATO rounds.