What is My Gun Chambered In?
This video explains how to identify the caliber of a firearm. For pistols, the caliber is usually marked on the barrel hood, as demonstrated with a Glock 9x19. Rifles, particularly AR-15s, typically have the caliber stamped on the barrel, often near the gas block. The common 'CAL. MULTI' marking on AR-15 lower receivers indicates compatibility, not the actual chambering, which is determined by the barrel (e.g., 5.56 or .223).









