Some available calibers for the AR-15 are the .223 Remington/5.56x45mm, .300 Blackout, .45 ACP, 5.7x28mm, 6.5 mm Grendel, 6.8 mm Remington SPC, .50 Beowulf, .50 BMG, and .458 SOCOM.
* Barrett REC7 — вариант с коротким ходом поршня, под патроны 5,56 мм и 6,8×43 мм Remington SPC.