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.
- Product
- Qty in Cart
- Quantity
- Price
- Subtotal
-
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 -
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 -
On Sale
HK MP5K Trunnion - 9mm
HKP HK Parts
Now: $45.95Was: $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-17964Now: $45.95Was: $57.95 -
AR-15 Mil-Spec Buffer Tube Kit
HKP HK Parts
$42.95Mil-Spec Buffer Tube Kit Compatible With: AR-15 style platforms Not correct length for HK rifles Includes: Made with T7 7075 aircraft-grade aluminum Made in the USA with a polished inside tube Mil-Spec triple hard coat Teflon anodized...HKP-02735$42.95 -
On Sale
HK MP5, MP5K Rear Sight Base - Billeted
HKP HK Parts
Now: $13.95Was: $17.95HKP HK Parts Billeted Rear Sight Base - Weldment for HK MP5 and HK MP5K 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...HKP-18087Now: $13.95Was: $17.95 -
On Sale
Picatinny Rail for HK Receivers - 13 Slot
DTAC Dakota Tactical
Now: $62.95Was: $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-17818Now: $62.95Was: $74.95 -
HK UMP Magazine Release Axle
H&K Heckler & Koch
$19.95Heckler and Koch Magazine Release Axle for HK UMP Replacement magazine release axle for HK UMP platforms. This component is commonly replaced due to wear or breakage and may also be required when configuring compliant magazine release systems where...HKP-02159$19.95 -
On Sale
HK21, FMP21 Teardrop Rail Set - T-Rail
HKP HK Parts
Now: $157.95Was: $197.95HKP HK21/FMP21 Teardrop Rail Set HK teardrop style reinforcement rails. The ultimate choice for period correct builds. Expertly crafted in the USA from high-quality 4140 steel, these ready-to-weld rails are engineered for precision and durability...HKP-21671Now: $157.95Was: $197.95 -
Out Of Stock
HK416, MR556, HK417, MR762 Bridge
H&K Heckler & Koch
$24.95Heckler and Koch HK416, HK MR556, HK417, and MR762 Bridge For Lowers Compatible With: HK416, MR556 HK417, MR762HKP-02676$24.95 -
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 -
HK MR556 A4 Upper Receiver Kit - 16.5″ - 5.56 - M-LOK
H&K Heckler & Koch
$1,939.00H&K MR556 A4 16.5″ 5.56 M-LOK Upper Receiver Kit 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 system utilizes a piston...HKP-21909$1,939.00 -
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