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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On Sale
HK MP5K Side Reinforcement Tabs
USA
Now: $11.95Was: $14.95HK MP5K Side Reinforcement TabsHKP-20168Now: $11.95Was: $14.95 -
On Sale
HK UMP Paddle Magazine Release - Extended
HKP HK Parts
Now: $27.95Was: $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-17919Now: $27.95Was: $34.95 -
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 -
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 -
HK417, MR762, G28 E1 Charging Handle - Extended - Ambidextrous
H&K Heckler & Koch
$209.95H&K HK MR762/417/G28 E1 Extended Ambidextrous Charging Handle HK German MR762/HK 417 extended charging handle. The unique release latch can be swapped from left to right sides to make each setup ambi friendly and modular. HK's own design boasts an...HKP-16599$209.95 -
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 -
On Sale
HK91, G3, HK33, HK53, HK93 Paddle Magazine Release - Anti-Rattle
MKE
Now: $27.95Was: $32.95MKE Anti Rattle Paddle Magazine Release for HK91, HK G3s and HK33, HK53, HK93 Upgrade your rifle with MKE's anti-rattle style paddle mag release. Compatible With: HK91, G3 HK33, HK53, HK93 PSG1, MSG90 In-spec clones and custom buildsHKP-99348Now: $27.95Was: $32.95 -
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 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 -
$7.95 -
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