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,...$129.95 -
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 -...$489.95 -
HK MP5 Case Deflector - 9mm, .40 S&W Receivers
HKP HK Parts
$24.95HKP HK MP5 Case Deflector - 9mm, .40 Receivers US-made steel case deflector for HK MP5 and MP5K receivers in 9mm and .40 S&W. Installs on the ejection-port flat, rivet or weld, to redirect brass and support reliable extraction on MP5 and MP5K style...$24.95 -
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 HK417$797.95 -
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...$1,285.95 -
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 pin$68.95 -
HK FMP G3 Rear Receiver Section - SURPLUS
FMP HK CONTRACT
$24.95H&K G3 Complete Parkerized Rear Receiver Section without Rear Sight - SURPLUS UNIT CONDITION WILL VARY Steel rear receiver section manufactured by FMP on HK tooling. Does not include the rear sight. Compatible with: HK G3, HK91 In-spec...$24.95 -
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/A4$95.95 -
HK MR556 A4 Complete Upper - F/A & Ejection Door
H&K Heckler & Koch
$845.95H&K HK MR556 A4 Complete Upper w F/A Ejection Door The H&K 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 and precision. This...$845.95 -
HK416, MR556 Complete Buffer Tube
H&K Heckler & Koch
$176.95H&K HK416, MR556 Complete Receiver Extension/Buffer Tube Genuine German complete receiver extension for the 416 based 5.56 / .223 platforms. Compatible With: HK416 MR556$176.95 -
HK UMP Demilled Extended Rear Receiver Section
H&K Heckler & Koch
$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...$999.95 -
HK417, MR762 Charging Handle Plate
H&K Heckler & Koch
$19.95HK MR762, HK417 Plate For Charging Handle Compatible With: HK MR762 HK417$19.95