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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HK91, G3 Magazine Release - Anti-Rattle - Surplus
H&K Heckler & Koch
$24.95Heckler and Koch Anti-Rattle Mag Release from Surplus for HK G3, HK91, PTR, HK33, HK53, HK93 Pulled from demilled German HK firearms. Once refinished this item can be made to look like new. For install on all HK Rifles caliber .223 and .308. This is the...HKP-17855$24.95 -
HK33, HK93, HK51, HK91, G3 Paddle Magazine Release - Standard
H&K Heckler & Koch
$8.95New Heckler and Koch Paddle Magazine Release This item is a brand new HK German genuine part, not a used or surplus part. It's used for installation on all HK .223 and .308 rifles. Compatible With: HK91, G3 HK 51 HK33, HK93 PSG1, MSG90HKP-01851$8.95 -
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 -
HK MP5, SP5, HK90 Series Paddle Mag Release Bushing - Full Auto - 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 -
Out Of Stock
HK SP5K Mag Release Upgrade Kit - 9mm - Drop In Paddle
HKP HK Parts
$74.95HKP HK Parts Anti-Rattle Roller Tipped "Paddle" Magazine Release Install Kit for HK SP5K 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...HKP-18192$74.95 -
HK416, MR556 Buffer Tube Castle Nut - A5 Extended
H&K Heckler & Koch
$75.95Heckler and Koch A5 Factory German Extended Castle Nut for HK416 and HK MR556 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 -
HK UMP Paddle Magazine Release
H&K Heckler & Koch
$16.95Heckler and Koch Paddle Magazine Release for HK UMP 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 Please...HKP-00810$16.95 -
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 -
HK416, MR556, HK417, MR762 Detent Takedown Pin
H&K Heckler & Koch
$9.95Heckler and Koch HK417, HK MR556, HK417, HK MR762 Detent Takedown Pin Factory H&K takedown pin for MR556 A4. Compatible With: HK416, MR556 HK417, MR762HKP-02540$9.95 -
HK416, MR556, HK417, 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 -
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