The 16.1 5.7x28mm Barrel and BCG Kit is just the thing for building a carbine length AR in 5.7x28mm using CMMGs patented Radial Delayed Blowback operating system. Unlike typical direct blowback systems, Radial Delayed Blowback not only reduces the weight in your BCG but it results in less felt recoil than a straight blowback system without sacrificing key features like last round bolt hold open. CMMGs 5.7x28mm Barrel and Bolt Kits are designed to be assembled into a Mk4/mil-spec AR15 upper and work with either a CMMG Mk57 lower receiver or Mk4/AR15 mil-spec lower receiver (when using CMMG 5.7 AR Conversion Magazines).
Specifications:

Caliber or Gauge
Length	16.10"
Model	Replacement Barrel
Twist
Sights
Bore Type
Finish	Salt Bath Nitride
Type
Chokes Included
Choke Configuration
Barrel Type
Ammo Type
Barrel Features