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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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 -
HK417, MR762, G28 Castle Nut for Buffer Tube - Extended
H&K Heckler & Koch
$85.95HK G28 Buffer Tube Castle Nut New HK German G28 castle nut for the HK MR762, HK417 & G28 models. Black in color. This is the proper part for use with the G28 buffer tube and stock upgrades. Compatible With: HK MR762 HK 417 HK G28 DMRHKP-16763$85.95 -
HK416, MR556 Ejector Port Cover Pin
H&K Heckler & Koch
$19.95HK MR556 & 416 Ejector Port Cover Pin Compatible With: HK MR556 HK 416HKP-02661$19.95