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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Out Of Stock
HK416, MR556 Upper 9" 416C Style Conversion Kit
HKP HK Parts
$899.95MR556 & HK416 Upper Conversion Kit - 9" - HK 416C Style Finally an answer for all of those that have been wanting as close to the original, rare unicorn of a find HK 416C 9" barrel conversion kit for 416 or MR556. Each conversion kit upper or barrel...HKP-18674$899.95 -
Out Of Stock
HK USC Magazine Release - Extended - .45 ACP
HKP HK Parts
$24.95HK USC Alloy Mag Release - Extended Billeted alloy USC magazine release. This is a very common repair & replacement part as they are fairly easy to break on the USC lower. With this new metal mag release you get more surface area as well as a much...HKP-17918$24.95 -
Out Of Stock
HK UMP (.40 S&W/.45 ACP/9mm) Demilled Rear Receiver Section
H&K Heckler & Koch
$0.00HK UMP Demilled Receiver Section This is a demilled factory HK UMP rear receiver section that is perfect for the new Tom Bostic USC-UMP conversions. This section is the perfect length in order to do the USC/UMP conversion. Last one available.HKP-01659$0.00 -
Out Of Stock
HK UMP Paddle Magazine Release
$9.95UMP Paddle Magazine Release - US Made New UMP Mag release. This is a very common repair & replacement part as they are fairly easy to break on the UMP lower. Simple & easy to install no gunsmith needed or required. Compatible With: UMP .45 UMP ...HKP-18773$9.95 -
Out Of Stock
MM HK 21 (7.62x51/.308) Trunnion
H&K Heckler & Koch
$0.00US Made HK21 Trunnion By Michael's Machine (MM) These are the finest US-made trunnions available.HKP-00246$0.00 -
Out Of Stock
HK23E Feed Mechanism - Complete - 5.56 / .223
Michaels Machines
$3,999.95MM HK 23E (5.56/.223) Complete Feed Mechanism New US manufactured HK23E feed mechanism complete with top plate and push pin. The complete unit a great spare to have on hand. Compatible With: Factory HK23E and MM23E firearmsHKP-17578$3,999.95 -
Out Of Stock
HK33, HK53, HK93 Paddle Magazine Release Set Complete-Used
H&K Heckler & Koch
$0.00HK 93, HK33, & HK 53 Paddle magazine release set complete all pieces-UsedHKP-00707$0.00