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
HK MR556 A4 Upper Receiver Kit - 11"- M-LOK
H&K Heckler & Koch
$1,998.95H&K Heckler & Koch MR556 Upper Receiver Kit A4 -11″ - M-LOK This kit includes a complete upper receiver/barrel assembly, allowing Mil-Spec 5.56mm AR-style rifles to be retrofitted to HK’s piston and...HKP-21910$1,998.95 -
Out Of Stock
HK MP5, MP5K Paddle Mag Release Contact Piece
H&K Heckler & Koch
$59.95Heckler and Koch 9mm Contact Piece for Paddle Mag Release for HK MP5 and HK MP5K - German This is the real deal NOT the .308 or .223 contact piece. Hard to find factory-correcHKP-00118$59.95 -
HK MP5K, SP5K Rear Push Pin Weldment Set
USA
$14.95HK MP5K, SP5K Rear Push Pin Weldment Set This weldment set is the 2 pieces needed for the rear of the flat/receiver that holds the stock/brace or end cap in place. CNC machined from weldable steel...HKP-19632$14.95 -
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...HKP-00465$29.95 -
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 G36KHKP-18254$4.95 -
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 SL8<HKP-16344$9.95 -
Out Of Stock
HK Semi Auto Shelf, Hanger Block For Receiver
HKP HK Parts
$13.95HK Semi Auto Shelf Weldment, Hanger Block Weldment HK Semi Auto Shelf, Hanger Block to HK's factory specifications for c/p trigger housings. Weld on shelf that is the needed receiver block that welds...HKP-17572$13.95 -
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: USCHKP-01899$9.95 -
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...HKP-18109$9.95 -
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...HKP-18499$199.95 -
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...HKP-01058$94.99 -
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...HKP-20921$189.95