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Questions & Answers
is the muzzle 1/2x28

Can I use my regular AR15 Upper and Lower?

by Ortega, Verified Owner, August 25, 2025
What gas block do u recommend for ar platform

no gas block needed

by Matt, Verified Owner, March 25, 2025

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Product Info for CMMG 57 X 28mm Barrel And Bcg Kit

The 5 5.7x28mm Barrel and BCG Kit allows you to build an 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. CMMGs 5.7x28mm Barrel and Bolt Kits are designed to be assembled into a mil-spec AR15 Upper and work with either a CMMG Mk57 lower receiver or with a standard Mk4/AR-15 lower receiver (when using CMMG 5.7 AR Conversion Magazines).image

WARNING: California`s Proposition 65

Specifications for CMMG 57 X 28mm Barrel And Bcg Kit:

Manufacturer: CMMG
Color: Black
Finish: No
Fabric/Material: 4140CM
Caliber: 5.7x28mm
Flutes: No
Condition: New

Package Contents:

  • CMMG 57 X 28mm Barrel And Bcg Kit

CMMG 57 X 28mm Barrel And Bcg Kit Orderable Models

List of Orderable Models

  • CMMG Barrel and BCG Kit, 5in, 4140CM, SBN, 57 x 28mm, 57DBC33 , MPN: 57DBC33 , UPC: 810097502390 , Code: 2CM-ATB-CP11-57DBC33
  • CMMG Barrel and BCG Kit, 8in, 4140CM, SBN, 57 x 28mm, 57D88C3 , MPN: 57D88C3 , UPC: 810097502406 , Code: 2CM-ATB-CP11-57D88C3
  • CMMG Barrel and BCG Kit, 16.1in, 4140CM, SBN, 57 x 28mm, 57D0476 , MPN: 57D0476 , UPC: 810097502413 , Code: 2CM-ATB-CP11-57D0476

CMMG 57 X 28mm Barrel And Bcg Kit Unavailable & Discontinued Models

List of Unorderable Models

  • USED CMMG Barrel and BCG Kit, 5in, 4140CM, SBN, 57 x 28mm, 57DBC33, EDEMO1, Used, Condition Good , MPN: 57DBC33-EDEMO1 , Code: 2CM-ATB-CP11-57DBC33-EDEMO1
  • DEMO, CMMG Barrel and BCG Kit, 16.1in, 4140CM, SBN, 57 x 28mm, 57D0476 , MPN: 57D0476-DEMO , Code: 2CM-ATB-CP11-57D0476-DEMO
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