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
HK MP5K Receiver Flat - Smooth Top
HKP HK Parts
$129.95HKP HK MP5K Receiver Flat - Smooth Top The MP5K receiver flat has been meticulously crafted by the original German tool and die maker of the LSC receiver flat, utilizing factory original German prints and specifications. This receiver boasts a flat top,...HKP-21550$129.95 -
On Sale
HK UMP Demilled Extended Rear Receiver Section
H&K Heckler & Koch
Now: $689.95Was: $999.95HK German Factory UMP Receiver Section - Extended Demilled factory HK UMP rear receiver section perfect for a USC-UMP conversion. With the folding stock attachment point intact right in front of the ejection port, this extended receiver section is...HKP-19798Now: $689.95Was: $999.95 -
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 -
HK FMP G3 Early Type De-Milled Front End - No Cocking Handle Assembly
FMP HK CONTRACT
$68.95HK G3 - FMP Early Type De-milled Front End - No Cocking Handle Assembly Early style G3 front end with no hanger from de-milled FMP G3 parts kits. Perfect for custom builds. Includes: Cocking tube Trunnion Barrel pinHKP-22377$68.95 -
HK MR556 A4 Upper, Complete - Full Auto and Ejection Door
H&K Heckler & Koch
$845.95HK Heckler and Koch A4 Complete Upper with Full Auto Ejection Door for HK MR556 The HK MR556 A4 Complete Upper is a superior factory assembly that comes fully equipped with a forward assist and an ejection port door, providing unparalleled reliability...HKP-21929$845.95 -
HK417, MR762 Upper Receiver - Incomplete
H&K Heckler & Koch
$797.95H&K HK MR762/417 Upper Receiver - Incomplete Stripped upper receiver with threaded piston guide bushing installed. Compatible With: HK MR762 HK417HKP-16624$797.95 -
HK417, MR762 Charging Handle Plate
H&K Heckler & Koch
$19.95HK MR762, HK417 Plate For Charging Handle Compatible With: HK MR762 HK417HKP-16843$19.95 -
Out Of Stock
HK416, MR556 Upper 8" 416C Style Conversion Kit
HKP HK Parts
$1,285.95Upper Conversion Kit for HK416 and MR556 8 inch barrel - HK 416C Style Finally an answer for all of those that have been wanting as close to the original, rare unicorn of a find HK 416C 8" barrel conversion kit for 416 or MR556. Each conversion kit...HKP-18629$1,285.95 -
HK21 Barrel Grip Axle Pin
H&K Heckler & Koch
$9.95HK21 Barrel Grip Axle Pin Factory axle pin for HK21 barrel handle release levers.HKP-15451$9.95 -
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 -
On Sale
HK416 Upper Receiver Assembly - 14.5" Barrel - OTB - Unfired
H&K Heckler & Koch
Now: $9,999.95Was: $14,499.95Heckler and Koch Unfired "BF" Date Coded HK Factory German 416 14.5" Upper Kit No FFL is required. This upper assembly is only considered a part. This is a rare offering. All NFA rules apply - Check your local short barrel rifle regulations...HKP-02095Now: $9,999.95Was: $14,499.95 -
HK MP5K, AP5-P Trunnion - 9mm
MKE
$79.95HK MP5K 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: MP5K In spec clonesHKP-22522$79.95