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
HK417, MR762 Upper Receiver Rod Tool
MI Midwest Industries
Now: $135.95Was: $159.95Midwest Industries Upper Receiver Rod Tool for HK417, MR762 Receiver support rod for HK417 and MR762 upper receivers. Designed to prevent receiver and index-pin damage during barrel nut removal, muzzle device installation, and other high-torque...HKP-22353Now: $135.95Was: $159.95 -
HK416, MR556 Takedown Pin - Front - A4 Style
H&K Heckler & Koch
$26.95H&K HK416, MR556 A4 Front Takedown Pin The HK416 front takedown pin is a German-made component designed to securely fasten the upper and lower receivers. Precision-machined for a proper fit, it ensures reliable function and serves as an ideal...HKP-21862$26.95 -
On Sale
HK MP5 Receiver Flat - Smooth Top
HKP HK Parts
Now: $99.95Was: $125.95HKP HK MP5 Receiver Flat - Smooth Top The MP5 receiver flat has been meticulously crafted by the original German tool and die maker of the LSC receiver flat, utilizing factory original German prints and specifications. This receiver boasts a flat top,...HKP-21552Now: $99.95Was: $125.95 -
HK G36, SL8 Recoil Spring Assembly, Complete
H&K Heckler & Koch
$69.95Recoil Rod Assembly for HK G36 & SL8 New HK factory German G36/SL8 (fits all variants of SL8/G36) recoil rod assembly complete. Great for replacement or for a spare as these have been hard to find.HKP-01057$69.95 -
Out Of Stock
HK416, MR556, MR762, AR-15 Take Down Pin Set - Titanium
HKP HK Parts
$29.95AR15, M4, MR556, MR762, AR10 Enhanced Take Down Pin Set Front & Rear - Titanium Custom ultra strong pure titanium front and rear take down pin set. Each set included both the front and rear pins for any AR mil-spec style lower. Compatible...HKP-17936$29.95 -
On Sale
HK UMP Magazine Release - Enhanced - Billeted
HKP HK Parts
Now: $27.95Was: $34.95HKP HK Parts Enhanced Paddle Magazine Release for HK UMP 9mm, .40 S&W, .45 ACP This is a very common replacement part as they are fairly easy to break on the UMP lower. With this new mag release, you'll get a wider release as well as a much more...HKP-18758Now: $27.95Was: $34.95 -
Out Of Stock
HK MR556 Upper Receiver Kit -16.5" - M-LOK
H&K Heckler & Koch
$1,779.95New HK Factory German MR556 Upper Kit with M-LOK forearm Includes: Complete MR556 upper receiver with M-LOK forearm MR556 Bolt group Complete Tungsten Filled HK Buffer HK Buffer Spring One 30 Round HK Steel Maritime Magazine No FFL required as the...HKP-17366$1,779.95 -
HK417, MR762 QD End Plate - Flush Cup
H&K Heckler & Koch
$174.95H&K HK MR762/417 Flush Cup QD End Plate Factory HK flush end cap with dual QD sockets for ambidextrious sling attachment. Compatible With: HK MR762 HK 417HKP-21642$174.95 -
On Sale
HK G36, SL8 Cocking Handle Axle Pin - USA
USA
Now: $7.95Was: $10.95HK G36, SL8 Cocking Handle Axle Pin - US Made This is the rivet pin that is used to attach the swiveling cocking handle to the body of the carrier. These can be replaced as they break and wear. Compatible With: HK G36 models HK SL8 modelsHKP-18367Now: $7.95Was: $10.95 -
HK91, G3 Magazine Release Set, Complete - USED
H&K Heckler & Koch
$24.95Heckler and Koch Magazine Release Set (Left to Right) for HK91 and G3 This HK German manufactured, used magazine release set for HK .308 pattern rifles consists of 6 pieces. Complete left-to-right mag catch assembly with both push-button and paddle...HKP-22466$24.95 -
On Sale
HK MP5 Paddle Magazine Release Lever - .40 S&W, 10mm
HKP HK Parts
Now: $47.95Was: $59.95HKP HK Parts Magazine Release Lever for .40 S&W and 10mm HK MP5 Compatible with MP5HKP-01274Now: $47.95Was: $59.95 -
Out Of Stock
HK MR556, MR223 Upper Receiver - Forward Assist and Ejection Door
H&K Heckler & Koch
$694.95New HK German Partially Pre-Assembled Upper Receiver for HK MR556 and HK MR223 Each unit comes just as shown with the F/A (forward assist) assembly and ejection port door assembly installed from the HK factory. Compatible...HKP-16950$694.95