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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HK G3/HK91 Anti-Rattle Mag Release - Surplus
H&K Heckler & Koch
$24.95H&K HK G3, HK 91, PTR, HK 93, HK 53, HK 33 Anti-Rattle Mag Release - Surplus Pulled from demilled German HK firearms. Once refinished this item can be made to look like new. For install on all HK .223 & .308 HK Rifles. This is the highly desired...HKP-17855$24.95 -
HK416, HK417, MR556, MR762 Takedown Pin Detent Spring
H&K Heckler & Koch
$9.95H&K HK MR556/MR762/416/417 Takedown Pin Detent Spring New HK German manufacture. Detent spring for the rear takedown pin. Compatible With: HK MR556 HK 416 HK MR762 HK 417HKP-02541$9.95 -
HK33, HK93, HK51, HK91, G3 Paddle Mag Release - Standard
H&K Heckler & Koch
$8.95New HK German Paddle Magazine Release This item is a brand new H&K genuine part, not a used or surplus part. It's used for installation on all HK .223 & .308 HK rifles. Compatible With: HK 91 HK G3 HK 51 HK 93 HK 33 HK PSG-1 HK MSG-90HKP-01851$8.95 -
HK 90 Series Paddle Mag Release - Easy Install Fixture
HKP HK Parts
$187.95HKP 90 Series Paddle Mag Release Easy Install Fixture The original one and only paddle mag release fixture. The perfect jig for the installation of the factory correct paddle mag release with the proper hole placement and an easy to use jig that will...HKP-17587$187.95 -
HK91, G3, HK33, HK93 Bayonet Adapter - Complete - Turkish Contract
Other
$38.95Turkish Contract Complete Bayonet Adapter for HK91, HK G3, HK33, HK93 Complete Turkish contract 90 Series-style steel bayonet adapter supplied with the required mounting hardware. Designed for proper fit on HK33, HK93, HK91, and G3 pattern rifles...HKP-22517$38.95 -
HK MP5, MP5K Scope Tab - Weldment
HKP HK Parts
$9.95MP5, MP5K Sight Tab - Weldment HK MP5, MP5K 17-4 Stainless H900 rear sight tab. The most correct MP5, MP5K rear sight base available. If you want your build to look as factory correct as possible then this sight base is an absolute must. Compatible...HKP-17503$9.95 -
Out Of Stock
HK SP5K Mag Release Upgrade Kit - 9mm - Drop In Paddle
HKP HK Parts
$74.95HK SP5K Anti-Rattle Roller Tipped "Paddle" Magazine Release Install Kit No modifications, no refinishing...complete drop-in kit included. New USA made busing for a drop-in install kit for the HK SP5K. This kit will allow any end-user to quickly,...HKP-18192$74.95 -
HK Full Auto Paddle Magazine Release Bushing HK German - Used
H&K Heckler & Koch
$4.95H&K Full Auto Paddle Magazine Release Bushing HK German - Used This part is for use in all 90-series H&K weapon systems. Used for installing a paddle mag release. Please Note: This is not for use on semi-auto HK builds. This part is used for...HKP-02303$4.95 -
HK416A5 Castle Nut - Extended
H&K Heckler & Koch
$75.95H&K HK416 A5 Factory German Extended Castle Nut Original HK Factory German steel 416 A5 Extended Castle Nut. Perfect for MR556, HK 416 A5 builds, or upgrades.HKP-19164$75.95 -
HK416, MR556 Mil-Spec Enhanced Buffer Tube
H&K Heckler & Koch
$254.95HK 416 & MR556 OTB (over the beach) Buffer Tube/Receiver Extension Each mil-spec buffer tube has built-in drainage holes in the rear of the tube and also on the bottom to maximize efficiency. Each buffer tube has ball-bearing rollers to tighten the...HKP-02716$254.95 -
HK416, HK417, MR556, MR762 Takedown Pin - Rear - A1 Style
H&K Heckler & Koch
$79.95H&K HK MR556/MR762/416/417 Rear Lower Receiver Locking Pin This is the rear 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 lower receivers and improve...HKP-02672$79.95 -
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