The M4-22 PRO Rifles by Tippmann Arms elevate the .22 caliber AR-15 platform by incorporating M4-inspired looks. From the aluminum upper to the lower receiver, most of it is Mil-Spec, so compatibility is wide for most AR-15 stocks, handguards and sights. Equipped with a 16" 4150 solid steel threaded barrel; a nickel-plated bolt for added reliability and adjustable flip-up sights.