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 G3 Rear Receiver Section with Rear Sight - Complete - Parkerized - SURPLUS
H&K Heckler & Koch
$54.95H&K G3 Complete Parkerized Rear Receiver Section w/ Rear Sight - SURPLUS UNIT QUALITY MAY VARY - SEE PHOTOS FOR EXAMPLE OF CONDITION RANGE Genuine H&K parkerized steel rear receiver section with fully installed G3 rear sight assembly, two stock...HKP-22164$54.95 -
HK MP5, MP5K Scope Tab - Billeted - Weldment
HKP HK Parts
$9.95HKP HK MP5/K Billeted Scope Tab - Weldment Billeted scope tab weldment for HK MP5, MP5K, and compatible clones. Provides a correct mounting point for optics. Compatible With: HK MP5/94 HK MP5K/SP89 HK MP5 40/10 Clones or custom buildsHKP-22063$9.95 -
HK UMP, USC Conversion Slide
H&K Heckler & Koch
$19.95HK USC & UMP Slide For Lower - German New HK German USC slide for conversion of UMP lower.HKP-00268$19.95 -
MM HK PSG1/21E/23E Forward Complete Assist Assembly
Michaels Machines
$779.95MM HK PSG1/21E/23E Forward Complete Assist Assembly Michael's Machines US-made complete forward assembly or your HK PSG1, MSG90, HK21E/23E. A great option for a build now that the factory units are no longer available. Available exclusively...HKP-00852$779.95 -
On Sale
HK MP5K Trunnion - Gunsmith Special
USA
Now: $24.95Was: $54.95HK MP5K Trunnion - Gunsmith Special US made HK MP5 trunnions sold as-is. Will require work before being functional. We recommend the work be performed by a professional gunsmith. The condition will vary from part-to-part vs. the pictured unit. Compatible...HKP-99090Now: $24.95Was: $54.95 -
HK USC Magazine Release Axle - .45 ACP
H&K Heckler & Koch
$18.95HK German USC Magazine Release Axle This is a great replacement as they are prone to breakage and wear. These are also a missing part in some states where bullet buttons are required. This part is compatible with all HK USC...HKP-02584$18.95 -
Out Of Stock
HK21 T-Rail Set - Factory Style
Michaels Machines
$275.00Michael's Machines HK 21 (7.62x51/.308) Factory Style T-Rail Set HK21 US-made rails for all HK21 builds. This is similar to the rails above, only prepped/cut for the HK21 feed mechanism.HKP-00823$275.00 -
HK MR762 A4 Upper Receiver Kit - 13"
H&K Heckler & Koch
$2,499.95HK MR762 A4 Upper Receiver Kit - 13" The MR762 A4 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 fouling and...HKP-22399$2,499.95 -
HK Receiver Flat Bending Set Jig - RENTAL
HKP HK Parts
$99.95Flat Bending Jig Set For All HK Style Receiver Flats - RENTAL Receiver flat bending jig RENTAL for all HK receiver flats. Our rental jigs are crafted in the US from billeted steel and include the latest revisions with proper dowel spacing for the...HKP-19595-RENTAL$99.95 -
HK MR762 Ejection Door Clamping Sleeve
H&K Heckler & Koch
$4.95H&K HK MR762 Ejection Door Clamping Sleeve Compatible With: HK MR762HKP-16518$4.95 -
$7.95 -
HK UMP Paddle Magazine Release - Extended
HKP HK Parts
$34.95UMP Paddle Magazine Release - Extended Billeted alloy UMP magazine release. This is a very common repair & replacement part as they are fairly easy to break on the UMP lower. With this new metal mag release you get more surface area as well as a much...HKP-17919$34.95