| Platform | Mk57 |
| Caliber | 5.7x28mm |
| Lower Receiver | Mk57 Forged 7075 T6 Aluminum |
| Finish | Cerakote |
| Trigger Guard | Integrated |
Please Allow 15-30 Days To Process Your Order.
State/local restrictions may apply in CA, CO, CT, DE, DC, HI, IL, MD, MA, MI, NJ, NY, or WA. Customers must review our Firearms Shipping Policy prior to ordering.
Firearms with attached pistol brace. Please confirm your FFL is accepting transfers for pistol brace equipped firearms prior to ordering.
Lower Receiver Assembly, Mk57
For those times you want to build your AR lower group exactly to your spec, the Mk57 Lower Receiver Assembly is here to fit the bill. Designed to accept AR15 accessories like trigger groups, safeties, and grips; this lower receiver pairs with our 5.7x28mm Radial Delayed Blowback upper groups and allows for maximum compatibility between your Mk57 build and other firearms that utilize FN®* Five-seveN®* pattern magazines.
We aim to please, that’s why every CMMG product is backed by our Lifetime Quality Guarantee against material and workmanship defects. Learn More.
**Mk57 Lowers are designed for use with CMMG 5.7x28mm Radial Delayed Blowback uppers only**
