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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HK416, MR556, AR-15 Buffer Tube Castle Nut
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: HK416, MR556 AR-15 style platformsHKP-02729$9.99 -
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 -
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 MP5, MP5K Magazine Release Paddle - Anti-Rattle Roller-Tip - 9mm
H&K Heckler & Koch
$64.95Heckler and Koch Anti-Rattle Roller Tipped "Paddle" Magazine Release for HK MP5, MP5K Factory German made Paddle mag release for all 9mm MP5, MP5K HK builds. Our parts are made by HK in Germany and are factory-fresh production. Compatible With: MP5,...HKP-00117$64.95 -
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 -
Out Of Stock
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 -
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 Castle Nut
H&K Heckler & Koch
$34.95Heckler and Koch Castle Nut for Buffer Tube for HK416 and HK MR556 New HK German manufacture. This buffer tube castle nut will fit both mil-spec and commercial buffer tubes. All steel manufacture. With HK round tool attachment points as well as...HKP-15230$34.95 -
On Sale
HK MP5 Receiver Flat - .40 S&W, 10mm
HKP HK Parts
Now: $194.95Was: $399.95MP5 40 & MP5 10mm Receiver Flat - USA The new and latest production with the weldment locations is already lasered and ready to go. This flat is the finest available for the MP5 40/10 family of firearms. Compatible With: MP5 .40 Cal MP5 10mm MP5 ...HKP-00767Now: $194.95Was: $399.95 -
HK MP5, MP5K Magazine Release Set
H&K Heckler & Koch
$184.95Heckler and Koch Magazine Release Set for HK MP5 and HK MP5K This is the complete magazine release kit that includes both the paddle mag release and standard left-to-right mag release on your HK 9mm rifle or pistol build. Set...HKP-02402$184.95 -
HK MP5 Receiver Flat- 9mm
LSC
$239.95MP5 Receiver Flat - PTR/LSC New PTR 9mm Receiver Flat made on the original LSC tooling. This flat is considered by many to be the most sought-after HK flat available on the market and perfect for that HK custom build. This item is not considered an FFL...HKP-01431$239.95