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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HK UMP Lower Locking Pin
HKP HK Parts
$12.95HK UMP Lower Locking Pin, Push Pin For use with all HK UMP lowers & USC to UMP conversions. Made in the USA. This is the pin that holds the lower to the receiver. Compatible With: UMP USC Conversions TBT builds Omega Other builds that...HKP-18580$12.95 -
HK MP5 Receiver Flat with Weldment Set - 9mm
HKP HK Parts
$219.95HKP HK MP5 9mm Receiver Flat with Weldment Set New MP5 receiver flat and weldment set combined for the best complete build option on the market. Made by the original German tool and die maker of the LSC receiver flat utilizing factory original German...HKP-20920$219.95 -
HK416, MR556 Ejection Port Cover
H&K Heckler & Koch
$55.95H&K HK MR556/416 Ejection Port Cover HK manufactured newer polymer style cover assembly found on the latest HK 416 & MR556. This item can also be used on other AR15-style projects to enhance the project with the finest ejection port cover...HKP-15229$55.95 -
HK416, MR556, HK417, MR762 Buffer Retaining Pin
H&K Heckler & Koch
$15.95Heckler and Koch HK MR556, HK MR762, 416/417 Buffer Retaining Pin New HK German proprietary HK designed buffer pin unique to the HK 416 and MR 556 series. Compatible With: HK416, MR556 HK MR762 HK M27HKP-02544$15.95 -
HK MP5 Trunnion - 9mm
RCM
$64.95RCM MP5 9mm Trunnion US made to exact factory HK specifications and machined completely from ordnance grade steel and heat treated to factory specs. Compatible With: MP5, 94 MP5K SP89 Clones or other custom buildsHKP-01193$64.95 -
HK SL8, G36 Magazine Release - Extended
H&K Heckler & Koch
$19.95Heckler and Koch Oversized Extended Magazine Release for HK SL8 and HK G36 New HK German HK SL8, HK G36, HK243 extended mag release. A must have upgrade for your HK SL8, SL8 to G36 conversion or G36 firearm. The HK extended magazine release is a...HKP-17720$19.95 -
HK MP5 Receiver Flat with Weldment Set
PTR
$294.95MP5 9mm Receiver Flat With Complete Weldment & Rivet Set - PTR/LSC Several years ago PTR bought out LSC and now owns the tooling and dyes for the LSC 9mm flats. These elusive flats have been hard to find and are now available for the first time here...HKP-19509$294.95 -
HK91, G3 Magazine Release Set
H&K Heckler & Koch
$34.95Heckler and Koch Magazine Release Set (Left to Right) for HK91, G3 This HK German manufactured magazine release set for HK .308 pattern rifles consists of 4 pieces. Includes: Magazine Catch Magazine Catch Spring Push Button Clamping Sleeve to retain...HKP-00929$34.95 -
HK MP5, MP5K Cartridge Case Deflector, Shell Deflector - Billet
HKP HK Parts
$19.95Cartridge Case Deflector, Shell Deflector - MP5, MP5K - Billet New US made case deflector for receiver flat or receiver for all MP5, HK94, MP5K, & SP89 builds. The case deflector is riveted or welded in place on the ejection port of the 9mm receiver...HKP-17574$19.95 -
HK MP5 Magazine Release - Extended Streamline - EMR
HKP HK Parts
$44.95HKP HK Parts Extended Magazine Release - EMR - Streamline for HK MP5 Elevate your paddle style mag release with the streamlined extended mag release. Crafted from a solid billet of aircraft-grade aluminum and featuring a hard anodized finish,...HKP-22175-M$44.95 -
HK91, G3, HK33, HK93 Bayonet Adapter - Complete - Turkish Contract
Other
$38.95Turkish Contract Complete Bayonet Adapter for HK91, HK G3, HK33, HK93 Complete Turkish contract 90 Series-style steel bayonet adapter supplied with the required mounting hardware. Designed for proper fit on HK33, HK93, HK91, and G3 pattern rifles...HKP-22517$38.95 -
HK416, MR556, HK417, MR762 Takedown Pin Detent Spring
H&K Heckler & Koch
$9.95H&K HK MR556/MR762/416/417 Takedown Pin Detent Spring New HK German manufacture. Detent spring for the rear takedown pin. Compatible With: HK MR556 HK 416 HK MR762 HK 417HKP-02541$9.95