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 MP5, MP5K 9mm Anti-Rattle Roller Tipped Paddle Magazine Release
HKP HK Parts
$29.47HK MP5, MP5K 9mm Anti-Rattle Roller Tipped Paddle Magazine Release Latest generation paddle mag release for all 9mm MP5, MP5K style builds. Made to the latest German specs, materials, and design. Compatible With: MP5, 94 MP5K, SP89, SP5K Other...HKP-17570$29.47 -
HK416, MR556, MR762 Buffer Retainer Pin
H&K Heckler & Koch
$3.95Heckler and Koch HK416, HK MR556, HK MR762 Buffer Retainer Pin Compatible With: HK416, MR556 HK MR762HKP-12704$3.95 -
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 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 -
HK SL8, G36 Extended Mag Release
H&K Heckler & Koch
$19.95HK SL8 & G36 Oversized Extended Mag Release New HK German SL8, G36, HK243 extended magazine release. A must have upgrade for your HK SL8, Sl8-G36 conversion or G36 firearm. The HK extended magazine release is a drop in replacement and requires zero...HKP-17720$19.95 -
HK91, G3 Mag Release Set
H&K Heckler & Koch
$34.95Heckler and Koch Magazine Release Set (Left to Right) for HK91, G3 This magazine catch set consists of 4 pieces and is HK-manufactured. Includes: Magazine Catch Magazine Catch Spring Push Button Clamping Sleeve to retain Push Button Compatible...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 - EMR - Streamline
HKP HK Parts
$44.95HKP HK MP5 Extended Magazine Release - EMR - Streamline 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, this lightweight...HKP-22175-M$44.95