H&K HK MR556/MR223 Upper Receiver w/ F/A & Ejection Door

New HK German Partially Pre-Assembled MR556/MR223 Upper Receiver

Each unit comes just as shown with the F/A (forward assist) assembly and ejection port door assembly installed from the HK factory. 

Compatible With:

• HK MR556
• HK MR223
• HK 416***

Need a matching lower for your build?  STS416 A5 LOWER - Specialized Tactical Systems

***Although this MR556 receiver is compatible with 416 lowers, the full-auto 416 bolt carrier group is not compatible with the MR556 upper receiver without modification to the upper receiver.  To pair this MR556 upper to a 416 lower without modification to the MR556 upper receiver, use the MR556 semi-auto bolt carrier group.***