gorilla 39Diameter: 39.00 mm; Thickness: 11.00 mm; With crown guards: 43.10 mm; Lug to lug: 50 mm; Water resistance: 100M330FT10ATM; Scratch resistant sapphire, double anti-reflectiveCheck out our special Gorilla Machining Mikhail AR-15 7.62x39 Barrel up. There are barrels of differing sizes and lengths that you can install easily on your rifle. Discover your perfect barrel