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 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-correct, brand-new, latest production German HK 9mm contact piece. Compatible...HKP-00118$59.95 -
On Sale
HK MP5K, SP5K Rear Push Pin Weldment Set
USA
Now: $11.95Was: $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 and the finest weldment available on the market...HKP-19632Now: $11.95Was: $14.95 -
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 to the rearward portion of the magwell to allow the...HKP-17572$13.95 -
On Sale
HK SL8, G36 Magazine Release Spring - US
GSG9
Now: $3.95Was: $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-18254Now: $3.95Was: $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 -
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 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 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 -
On Sale
HK MP5 Receiver Flat - 9mm
HKP HK Parts
Now: $151.95Was: $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-20921Now: $151.95Was: $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 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 pusher rod system. This...HKP-21910$1,998.95 -
On Sale
HK G36 Backplate, Complete - Recoil Buffer and Assembly
USA
Now: $71.95Was: $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-18537Now: $71.95Was: $84.95