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 MP5F Receiver Flat - Alternate Holes
HKP HK Parts
$125.95HKP HK MP5F 9mm Flat - Alternate Holes MP5 receiver flat crafted by the original German tool and die maker of the LSC receiver flat using factory original German prints and specifications. This receiver features alternate holes for the correct MP5F or...HKP-21551$125.95 -
HK MR556 Incomplete Upper Receiver
H&K Heckler & Koch
$449.95HK German Stripped HK MR556 Upper Receiver New factory German incomplete and unmarked MR556 upper receiver. Compatible With: HK MR556 HK MR223 HK 416 Do you need a matching lower for your build? STS416 A5 LOWER - Specialized Tactical...HKP-02615$449.95 -
HK33, HK53, HK93 Receiver Flat - Complete Weldment Set
HKP HK Parts
$229.95HK .223, 556, & 300 BLK Receiver Flat With Complete Weldment Set Combo Each flat and weldment set comes with 223/556/300BLK complete as a builders combo ready to assemble. Compatible With: HK93, HK33, & HK53 Style Builds 300...HKP-00006$229.95 -
HK416, MR556, MR762 Forward Assist Assembly
H&K Heckler & Koch
$74.95H&K HK MR556/MR762/416 Forward Assist Assembly H&K Germany factory MR556 & HK416 forward assist assembly complete. Compatible With: HK MR556 HK 416 HK MR762HKP-16528$74.95 -
HK21, HK11 Trunnion
RCM
$274.95RCM HK21 Trunnion When RCM set out to make a replacement trunnion for the venerable HK21, they started the process by putting a factory unit through rigorous destructive metal testing. The end-product: a US-made trunnion blending the proper...HKP-21609$274.95 -
HK416, MR556 Magazine Catch
H&K Heckler & Koch
$59.95H&K HK MR556/416 Magazine Catch New HK German manufacture magazine catch for the HK 416 and MR556 family of firearms. Compatible With: HK MR556 HK 416HKP-15458$59.95 -
HK416, MR556 Magazine Release Button
H&K Heckler & Koch
$16.95H&K HK MR556/416 Magazine Release Button New HK German Manufacture. Compatible With: HK MR556 HK416 AR15, M4 & M16 firearmsHKP-02656$16.95 -
HK416, MR556 Piston Guide - Threaded - Upper Receiver
H&K Heckler & Koch
$19.95HK MR556 & 416 Upper Receiver Threaded Piston Guide Compatible With: HK MR556 HK 416 HK M27HKP-02640$19.95 -
Out Of Stock
HK Semi Auto Shelf, Hanger Block For Receiver
HKP HK Parts
$13.95HK Semi Auto Shelf Weldment, Hanger Block Weldment HK Semi Auto Shelf, Hanger Block to HK's factory specifications for c/p trigger housings. Weld on shelf that is the needed receiver block that welds to the rearward portion of the magwell to allow the...HKP-17572$13.95 -
HK Magazine Release - HK45 & P30, P30L, P30SK
H&K Heckler & Koch
$15.95H&K Magazine Release Compatible With: HK45 HK45 Tactical HK P30, P30S, P30L, P30SK Please Note: This part will not fit pistols other than the ones listed above.HKP-01809$15.95 -
Out Of Stock
HK416, HK417, MR556, MR762 Forward Assist Plunger Spring
H&K Heckler & Koch
$5.95H&K HK MR556/MR762/416/417 Forward Assist Plunger Spring New HK German manufacture. Compatible With: HK MR556 HK 416 HK MR762 HK 417 HK G28 HK M27HKP-02537$5.95 -
HK MP5K, SP5K Rear Push Pin Weldment Set
USA
$14.95HK MP5K, SP5K Rear Push Pin Weldment Set This weldment set is the 2 pieces needed for the rear of the flat/receiver that holds the stock/brace or end cap in place. CNC machined from weldable steel and the finest weldment available on the market...HKP-19632$14.95