The Mk57(TM) DISSENTmay beat the Mk4 5.7x28mm DISSENT in the smallest mag footprint, the Mk4 DISSENT shows its capability with the Mk4 lower. The standard AR15/Mk4 lower receiver uses our 5.7 AR Conversion mags, resulting in 32rd~ capacity and a lower that& ready to pair with a different caliber DISSENT upper and matching magazine.Available in a variety of custom Cerakote finish options; the rear of the DISSENT SBR features the DISSENT side folding stock with adjustable length of pull and adjustable cheek riser. A forward non-reciprocating charging handle allows for quick and easy manipulation without coming off target and the M-LOK handguard with top picatinny rail provides ample mounting space for whatever accessories you please.Compact Action Radial Delayed Blowback(TM) Operating SystemOriginally developed for the .45 ACP MkG platform, CMMG has adapted our Radial Delayed Blowback system across our pistol caliber lineup to create pistols and rifles with a softer recoil impulse and reduced bolt weight compared to traditional straight blowback systems. Now with the advent of our patented Compact Action in every DISSENT, Radial Delayed Blowback can be had in bufferless form.Check out our CMMG Resources article & video to learn more about what sets Radial Delayed Blowback apart.Lifetime Quality GuaranteeWe aim to please, that's why every CMMG product is backed by our Lifetime Quality Guarantee against material and workmanship defects.Learn More.**All NFA rules apply** NFA Rules Apply All DISSENT SBRs (short barrel rifles) require additional ATF paperwork & processing time. See linked CMMG Resource article for more information.Learn more about NFA rules.~ Firearms shipping to states with magazine capacity restrictions will only ship with 10rd magazines in place of standard capacity magazines. CMMG does not address any other state compliancy requirements for further restricted states.