By exceeding military standards, Core Systems ensures the best fit possible and can offer a more reliable, smoother functioning, and more accurate weapon that will provide you with the peace of mind that you deserve. The Core 15 Piston has gas piston assembly with adjustable gas settings and a proprietary monolithic, melonite-coated bolt carrier that ensures unquestionable performance in any environment. The 16" M4 profile stainless steel match-grade barrel has a 1 in 8" twist and comes mated with a Mil-Spec forged 7075-T6 upper and lower receiver and a Magpul MOE six-position stock with a pistol grip. The lower receiver has a beveled magwell for improved reloading speed, machined chevrons in front strap, and bullet pictogram safety markings. The upper receiver has M4 feed ramps and a 1913 Picatinny flat top rail. A Core 15 V.2 Hardcore Billet charging handle and oversized trigger guard, a free-floating quad rail, and Magpul MOE MBUS front and rear sights make the Tac M4 Piston ready to fire out of the box. A 30-round Magpul PMAG is included.