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 G36 Backplate Complete w/ Recoil 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 -
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 MP5K Trunnion - 9mm
HKP HK Parts
$57.95HK MP5K Trunnion - USA US made to exact factory HK specifications for the HK MP5K type builds. Machined completely from ordnance grade steel and heat treated to factory specs. These are the best USA made trunnions on the market. Machined to HK spec...HKP-17964$57.95 -
HK Mil-Spec Buffer Tube Kit
HKP HK Parts
$42.95Mil-Spec Buffer Tube Kit Compatible With: HK MR556 & 416 AR-15 style platforms Includes: Made with T7 7075 aircraft-grade aluminum Made in the USA with a polished inside tube Mil-Spec triple hard coat Teflon anodized finish Each unit comes with a...HKP-02735$42.95 -
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 -
HK MP5, MP5K Rear Sight Base - Billeted
HKP HK Parts
$17.95Billeted MP5, MP5K Rear Sight Base - Weldment All steel HK MP5, MP5K billeted rear sight base. The most correct MP5, MP5K rear sight base available. The only billeted factory correct sight base with the factory HK German side axis grooves. If you want...HKP-18087$17.95 -
Picatinny Rail for HK Receivers - 5.3" - Slot
DTAC Dakota Tactical
$74.95DTAC Picatinny Rail For HK Receivers - 13 Slot Mil-Spec all steel picatinny rail in the white, relief cut for HK receivers & made for mounting scopes and optics to HK builds. This unit easily welds to the top of your HK receiver. Compatible With: HK...HKP-17818$74.95 -
HK MP5, MP5K Contact Piece for Paddle Mag Release - 9mm
H&K Heckler & Koch
$59.95MP5, MP5K 9mm Contact Piece For Paddle Mag Release - 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 With: MP5, SP5, 94, SP5 MP5K, SP5K,...HKP-00118$59.95 -
HK91, G3 Trunnion - Used
H&K Heckler & Koch
$39.95HK German HK G3 & HK 91 Trunnion - Used These trunnions are from demilled G3 parts kits and will have leftover receivers and barrel stubs installed along with factory barrel pins. Please note the picture shows one with the demilled parts removed...HKP-00718$39.95 -
$19.95 -
HK UMP, USC Lower Locking Pin
H&K Heckler & Koch
$36.95HK German UMP Lower Locking Pin For use with all HK UMP lowers and USC to UMP conversions. New HK German manufacture.HKP-00595$36.95 -
HK416 E1, MR556 Charging Handle - RAL8000
H&K Heckler & Koch
$169.99New RAL 8000 HK Designed HK416, MR556 Ambidextrous Charging Handle (E1). The E1 HK 416 FDE charging handle release latch has the ability of being swapped from the left side (E1) to the right sight (E2) with simple tools. HK's own design boasts a smooth...HKP-18502$169.99