Selling an H&K MR556 A4 16.5in complete upper receiver in brand new condition. Has never been fired or connected to a lower. This is the genuine H&K factory upper, known for its exceptional piston-driven operation, reliability, premium construction, and the same engeineering lineage as the HK416. Includes all original accesories (H&K carry case, manual, complete upper with BCG assembly and charging handle). Model# 51000384.