- Complete MR556 A4 Upper Receiver/Barrel Assembly— HK 16.5 inch cold-hammer forged barrel, upper receiver with forward assist, extended convertible charging handle, HK Free Floating Rail System handguard
- Complete MR556 Bolt Group Assembly
- Tungsten Filled HK Proprietary Buffer
- HK Proprietary Buffer (Action) Spring
- Adjustable Gas Block
- Ships in HK Soft case.
Caliber: 5.56mm
Barrel: 16.5"
Finish: Black
Internal Reference:
51000384
Barcode:
642230270213
| Brand: H&K |
| Model: MR556 A4 |
| Caliber: 5.56mm |
| Part Type: Upper Receivers |
| Barrel Length: 16" - 36", 17" |
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