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 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.***