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
HK416 Upper Receiver Kit - 10.4" - Date Coded - OTB - USED
H&K Heckler & Koch
$3,789.95H&K 416 10.4" Date Coded OTB Upper Parts Kit - USED Genuine HK 416 10.4″ date coded used upper parts kit with a factory German 10.4″ barrel with the new Over The Beach (OTB) features (vented gas block, quad rail forearm). Finish...HKP-22193-M$3,789.95 -
On Sale
HK MP5 Receiver Flat - 9mm - no Sling Clip
HKP HK Parts
Now: $151.95Was: $189.95HKP HK MP5 9mm Receiver Flat w/o Sling Clip The MP5 9mm receiver flat serves as the foundation for custom MP5 builds. This version does not include a sling clip cutout, offering flexibility for customization. Precision-engineered for compatibility with...HKP-21828Now: $151.95Was: $189.95 -
HK MR762 A4 Buffer Tube
H&K Heckler & Koch
$95.95H&K MR762 A4 Buffer Tube Factory German-made buffer tube for the MR762 A4. Compatible With: HK MR762 A1/A4HKP-21964$95.95 -
HK23E, HK21E Rear Sight Base
H&K Heckler & Koch
$193.95Heckler and Koch Rear Sight Base HK21E and HK23E Genuine HK German rear site base. Requires post installation machining to accommodate a scope. Compatible With: HK21E HK23EHKP-21508$193.95 -
HK416 E1, MR556 Charging Handle - Incomplete
H&K Heckler & Koch
$109.95HK MR556, HK 416 E1/E2 Charging Handle - Incomplete New HK German manufactured HK MR556, HK 416. A great item to have on hand in the event of breakage or high wear. Compatible With: HK MR556 HK 416 HK M27HKP-17540$109.95 -
On Sale
HK MP5, MP5K, MKE AP5, AP5-P Case Deflector - 9mm Receivers
MKE
Now: $19.95Was: $24.95MKE AP5, AP5-P, HK MP5, MP5K Case Deflector for 9mm Receivers This steel case deflector is manufactured by MKE for AP5 firearms and fits MP5-pattern 9mm receivers. It installs on the ejection-port flat of the receiver and is riveted or welded in place to...HKP-99349Now: $19.95Was: $24.95 -
On Sale
HK G3 - FMP Early Type Demilled Front End
FMP HK CONTRACT
Now: $79.95Was: $99.95HK G3 - FMP Early Type Demilled Front End Early style G3 front end with no hanger. These are the perfect option for those doing custom builds. Good condition over all. Includes: Cocking tube Complete cocking handle assembly Trunnion Barrel pinHKP-20845Now: $79.95Was: $99.95 -
On Sale
Tommy Built UMP Buffer Tube Adapter
Now: $224.95Was: $249.95Tommy Built UMP Buffer Tube Adapter UMP hinge with Buffer Tube Mount for adapting an AR style Mil spec brace or stock. Constructed of nylon and has 6 adjustable positions. Adapter only- stocks in the pictures are for reference.HKP-19967Now: $224.95Was: $249.95 -
Out Of Stock
HK91, G3, PSG1, MSG90 T-Rail Reinforcement Set for Receiver
Michaels Machines
$299.95HK Receiver Reinforcement T-Rail Set For Left and Right Sides T-rails are used to strengthen HK receivers or for custom builds. These are the finest T-rails available on the market. Made from enhanced steel and perfect for that custom HK project...HKP-00236$299.95 -
Out Of Stock
HK MP5, HK94 Trunnion - 9mm - USA
HKP HK Parts
$54.95HKP MP5, 94 Trunnion 9mm - USA US made to exact factory HK specifications for the HK MP5, 94 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...HKP-17934$54.95 -
On Sale
HK MP5, AP5 Trunnion - 9mm
MKE
Now: $51.95Was: $64.95HK MP5 Trunnion Made to exact factory HK specifications for the HK MP5K type builds. Machined to HK spec making the install painless and hassle free. Compatible With: MP5 SP5 In spec clonesHKP-22523Now: $51.95Was: $64.95 -
HK MR762 A4 Upper Receiver Kit - 16"
H&K Heckler & Koch
$2,449.95HK UPPER RECEIVER KIT MR762 A4 - 16" The MR762 A4 upper kit contains a complete upper receiver and barrel assembly. The closed system design significantly reduces malfunctions typically associated with direct-impingement gas systems, as hot carbon...HKP-22424$2,449.95