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 -
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 -
HK MP5, MP5K, MKE AP5, AP5-P Case Deflector - 9mm Receivers
MKE
$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-99349$24.95 -
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 -
HK MR556, MR223 A5 Incomplete Upper Receiver
H&K Heckler & Koch
$489.95HK German Un-Assembled/Stripped HK MR556/MR223 A5 Upper Receiver Factory HK MR556 A5 upper receiver. This is the semi-auto MR556 variant. Compatible With: HK MR556 HK MR223 HK 416*** Need a matching lower for your build? STS416 A5 LOWER -...HKP-18785$489.95 -
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 -
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 -
HK91, G3, HK33, HK53, HK93 Paddle Magazine Release - Anti-Rattle - USED
H&K Heckler & Koch
$42.95Heckler and Koch Anti Rattle Paddle Magazine Release for HK91, HK G3s and HK33, HK53, HK93 - USED This is a used German anti-rattle paddle mag release for installation on all Heckler and Koch Firearms .223 and .308 rifles. Compatible With: HK91,...HKP-22061$42.95 -
On Sale
HK G3 - FMP Early Type Demilled Front End
FMP HK CONTRACT
Now: $63.72Was: $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: $63.72Was: $99.95 -
Tommy Built UMP Buffer Tube Adapter
$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-19967$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