Receivers / Flats / Uppers
Explore our premier selection of HK receivers, flats, and uppers at HKParts, perfect for building or upgrading your Heckler & Koch firearms. Our products feature precision-engineered MP5 receiver flats, HK 416 complete upper assemblies, and a wide range of custom options designed for tactical and precision shooting. Whether you are customizing an MP5, upgrading an HK416, or constructing a new firearm, our high-quality components provide unparalleled reliability and performance.
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Out Of Stock
HK416 E1, MR556 Charging Handle - Ambidextrous
H&K Heckler & Koch
$129.95H&K HK MR556/416 E1 Charging Handle - Ambidextrous HK's design boasts a smooth & easy to release latch with an enhanced oversized charging handle. Compatible With: HK MR556 HK 416 Other AR15, M4 & M16 applicationsHKP-01959$129.95 -
AR15 Castle Nut for Buffer Tubes
Ergo
$9.99Ergo AR-15 Castle Nut For Buffer Tubes - US Made Steel Castle-nut for AR buffer tubes fits both mil-spec and commercial buffer tubes alike. Compatible With: HK MR556 & 416 AR-15 style platformsHKP-02729$9.99 -
HK MP5K Picatinny End Plate Adapter
MI Midwest Industries
$89.95MI HK MP5K 1913 Picatinny End Plate Adapter The Midwest Industries Picatinny end plate adapter opens up a myriad of off-the-shelf stock and brace options. The adapter installs in the same manner as the factory end cap with the factory push pins...HKP-21584$89.95 -
Out Of Stock
HK91, G3, PTR Trunnion
RCM
$64.95RCM Trunnion For The HK91/G3 Series - US Made This part is machined from ordnance grade 9310 enhanced steel and heat treated to exact HK specifications. This item is the best USA-made trunnion on the market. Machined to spec and are to the custom ground...HKP-01289$64.95 -
HK416, HK417, MR556, MR762 Detent Takedown Pin
H&K Heckler & Koch
$9.95H&K HK MR556/MR762/416/417 Detent Takedown Pin Factory H&K takedown pin for MR556 A4. Compatible With: HK MR556 HK 416 HK MR762 HK 417HKP-02540$9.95 -
HK MP5, HK94 Case Deflector Rivet
H&K Heckler & Koch
$9.95H&K MP5, HK94 Case Deflector Rivet Each case deflector, US or German-made, will require two rivets to attach the case deflector to the receiver or flat. If you want the factory look and feel of doing it right, these rivets are a must-have. These are...HKP-00147$9.95 -
HK MR556 Receiver Take Down Tool
H&K Heckler & Koch
$19.95H&K HK MR556 Receiver Take Down Tool This part is the tool used to tighten down the stock movement on the E1/E2 stock. Each tool will be stored in the rear of the E1/E2 stock. Compatible With: HK MR556 Please Note: We get...HKP-02653$19.95 -
HK UMP Paddle Magazine Release
H&K Heckler & Koch
$16.95UMP Paddle Magazine Release This is a common repair and replacement part as they are easy to break on the UMP lower. Simple and easy to install with no gunsmith needed or required. Compatible With: UMP .45 UMP .40 UMP 9mm Please Note: This...HKP-00810$16.95 -
HK G36, SL8 Recoil Buffer - Factory - US
USA
$16.95HK G36 Or SL8 Factory Recoil Buffer A must have spare part as the buffer is prone to wear and breakage. Compatible With: All HK G36 models SL8 models ClonesHKP-18541$16.95 -
HK416, MR556 Buffer Tube Wrench
HKP HK Parts
$29.95HK MR556 & HK416 Buffer Tube Wrench The perfect metric wrench to remove and install the MR556 & HK 416 castle nuts on the buffer tube. A perfect addition to have on hand for OTB or other HK buffer tube upgrades, etc. Made from all steel, heat...HKP-17124$29.95 -
HK416, MR556 Receiver End Plate
H&K Heckler & Koch
$24.95HK 416, MR556 End Plate For Receiver & Buffer Tube New HK German manufacture. Compatible With: HK MR556 & HK 416 upper receiver/buffer tubesHKP-16603$24.95 -
HK416, MR556 Takedown Pin - Front - A1 Style
H&K Heckler & Koch
$64.95H&K HK MR556 Front Lower Receiver Locking Pin With Spring Loaded Detent This part is the front (large) takedown pin with ball detent and locking mechanism installed. The idea behind this type of system is to decrease the movement of the upper and...HKP-02663$64.95