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, 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 -
Out Of Stock
HK PSG1, HK21E, HK23E Forward Assist Assembly, Complete
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 -
$7.95 -
HK UMP Paddle Magazine Release - Extended
HKP HK Parts
$34.95HKP HK Parts Extended Paddle Magazine Release for HK UMP 9mm, .40 S&W, .45 ACP Billeted alloy UMP magazine release. This is a very common repair and replacement part as they are fairly easy to break on the UMP lower. With this new metal mag release...HKP-17919$34.95 -
HK33, HK53, HK93, HK91, G3 Paddle Magazine Release - Anti-Rattle
H&K Heckler & Koch
$64.95Heckler and Koch Anti Rattle Paddle Magazine Release This item is a new HK German genuine part not used or surplus for installation on all HK .223 and .308 HK rifles. This is the highly desired anti-rattle-style paddle mag release. Compatible...HKP-01126$64.95 -
HK MP5, HK94, SP5K Rear Sight Drum and Base
H&K Heckler & Koch
$109.95Heckler and Koch Rear Sight Drum and Base for HK MP5, HK94, and HK SP5K This is an HK German part that's a great upgrade for the SP5, SP5K, and SP89 or MP5K models. We highly suggest adding the following items to complete the rear sight set that's not...HKP-00073$109.95 -
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 -
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
H&K Heckler & Koch
$18.95Heckler and Koch .45 ACP Magazine Release Axle for HK USC Replacement magazine release axle for HK USC .45 ACP platforms. This component is commonly replaced due to wear or breakage and may also be required when configuring compliant magazine release...HKP-02584$18.95 -
Out Of Stock
HK33, HK53, HK93 Magazine Catch - Latest Design
H&K Heckler & Koch
$49.95Heckler and Koch German Factory Magazine Catch for HK33, HK53, HK93 New HK German HK33, HK53, and HK93 mag catch for magazine release. Compatible With: HK33, HK53, HK93 HK33K Clone or other custom buildsHKP-01059$49.95 -
On Sale
HK416 A1 Upper Receiver - 10.4"
H&K Heckler & Koch
Now: $2,999.95Was: $3,499.95HK416 10.4" Complete Upper Receiver Features: Factory German 10.4" length 2008 date coded P.D. trade-in, de-serialized during the de-milling process. Finish your build with a matching lower from STS Tactical. Compatible With: HK416HKP-22245Now: $2,999.95Was: $3,499.95 -
HK417, MR762 Charging Handle Pin
H&K Heckler & Koch
$6.95H&K HK MR762/417 Charging Handle Pin HK MR762 & HK 417 Clamping Sleeve for plate on charging handle. There are two of these pins used on the charging handle. Compatible With: HK MR762 HK 417HKP-16754$6.95