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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HK417, MR762, G28 Buffer Tube Castle Nut - Extended
H&K Heckler & Koch
$85.95Heckler and Koch Buffer Tube Castle Nut for HK G28, HK417 and HK MR762 New HK German G28 castle nut for the HK MR762, HK417, and G28 models. Black in color. This is the proper part for use with the G28 buffer tube and stock upgrades...HKP-16763$85.95 -
HK SL8, G36 Magazine Release Spring - US
GSG9
$4.95GSG9 Magazine Release Spring - USA Made for HK G36 and HK SL8 Mag release spring for all G36 and SL8 models. A must have spare part. Made in the USA. G36 G36K SL8 Other custom G36 type buildsHKP-18254$4.95 -
HK91, G3, HK33, HK53, HK93 Paddle Mag Release Contact Piece
H&K Heckler & Koch
$29.95Heckler and Koch Contact Piece for Paddle Magazine Release 5.56 / .223 and 7.62x51 / .308 German HK manufacture. The contact piece is used in the magazine release assembly for the paddle mag release. Compatible With: HK33, HK53, HK93 HK91, G3, PTR91HKP-00465$29.95 -
HK416A5 Stripped Upper Receiver
H&K Heckler & Koch
$489.99HK 416A5 - Stripped Upper Receiver This is the factory correct receiver for a true 416 build as it features the M16 relief cut in the bottom, rear portion of the receiver (shown in last pricture). Compatible With: HK 416 HK MR223 HK MR556 Need a...HKP-18786$489.99 -
HK MP5 Receiver Flat - 9mm
HKP HK Parts
$189.95HKP HK MP5 9mm Receiver Flat New MP5 receiver flat made by the original German tool and die maker of the LSC receiver flat utilizing factory original German prints and specifications. The creator of our receiver flat has been regarded as the premier flat...HKP-20921$189.95 -
HK G36 Backplate
H&K Heckler & Koch
$94.99HK G36 Backplate With Recoil Buffer This is a great spare or replacement to have on hand. These are also required for those that are doing the SL8-G36 conversions provided by Tommy Bostic & Chopstix Kid.HKP-01058$94.99 -
HK UMP, USC Magazine Release Spring
H&K Heckler & Koch
$9.95HK UMP & USC Magazine Release Spring HK German factory mag release spring for all USC and UMP mag releases. Compatible With: USC lowers UMP lowersHKP-01899$9.95 -
HK USC Magazine Release
H&K Heckler & Koch
$19.95Heckler and Koch .45 ACP Carbine Magazine Release for HK USC This is a great replacement as they are prone to breakage and wear. Please Note: For those that have a HK USC with a bullet button and are moving to a free state and want to revert back to the...HKP-02196$19.95 -
HK MP5 Magazine Release Lever Spring - .40 S&W, 10mm
H&K Heckler & Koch
$9.95HK Heckler and Koch Magazine Release Lever Spring for HK MP5 .40 S&W and 10mm The needed spring that fits in the mag release lever and the magwell for the MP5 40,10 series. Made in Germany and no longer offered or made. These units are the latest...HKP-18109$9.95 -
HK SL8, G36 Magazine Release Spring
H&K Heckler & Koch
$9.95Heckler and Koch Magazine Release Spring for HK G36 and HK SL8 A must have spare part. Compatible With: G36 SL8HKP-16344$9.95 -
HK G36 Backplate, Complete - Recoil Buffer and Assembly
USA
$84.95HK G36 Backplate Complete With Recoil Assembly New G36 Backplate with new G36/SL8 recoil buffer and recoil assembly. This assembly does include the recoil rod retaining screw. This is a great spare or replacement to have on hand. These are also required...HKP-18537$84.95 -
HK416, MR556 Buffer Tube - Enhanced
H&K Heckler & Koch
$199.95FDE HK 416, MR556 OTB (over the beach) Buffer Tube, Receiver Extension - Commercial Genuine HK German manufactured 416 & MR556 latest generation, marine environment & over the beach buffer tube. Each commercial buffer tube has built in drainage...HKP-18499$199.95