AT3 Tactical 5.56 NATO Government Profile 10.5 Inch AR-15 Barrel Black. 5 inch long 5.56 NATO barrel is a perfect match for a shorty AR-15 build that wont break the bank. This barrel has a corrosion-resistant black nitride finish with 4150 CMV steel construction for a long service life. The proven Government profile provides plenty of support for suppressors which are a natural fit for an SBR in this caliber. Specifications for AT3 Tactical 5.56 NATO Government Profile AR-15 Barrel: Manufacturer: AT3 Tactical Color: Black Caliber: 5.56x45mm NATO Barrel Profile: Government Gun Make: AR Platform Gun Model: AR-15 Package Contents: AT3 Tactical 5.56 NATO Government Profile AR-15 Barrel What firearm models does the manufacturer say AT3 Tactical 5.56 NATO Government Profile AR-15 Barrel is compatible with? The manufacturer suggests that AT3 Tactical 5.56 NATO Government Profile AR-15 Barrel is compatible with AR-15AT3 Tactical AT3-556-GOV-CAR-10.5: 5.56 NATO Government Profile 10.5 Inch AR-15 Barrel Black