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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HK416, MR556, MR762 Forward Assist Assembly, Complete
H&K Heckler & Koch
$74.95H&K Heckler and Koch Forward Assist Assembly for HK416, HK MR556, and HK MR762 H&K Germany factory HK MR556 and HK416 forward assist assembly complete. Compatible With: HK 416, MR556 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 -
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 -
Out Of Stock
HK416, MR556 Magazine Release Button
H&K Heckler & Koch
$16.95Heckler and Koch Magazine Release Button for HK416 and HK MR556 New HK German Manufacture. Compatible With: HK416, MR556 AR15, M4, M16 firearmsHKP-02656$16.95 -
HK416, MR556 Magazine Catch
H&K Heckler & Koch
$59.95Heckler and Koch Magazine Catch for HK416 and HK MR556 New HK German manufacture magazine catch for the HK 416 and MR556 family of firearms. Compatible With: HK416, MR556HKP-15458$59.95 -
HK416, MR556 Piston Guide - Threaded - Upper Receiver
H&K Heckler & Koch
$19.95Heckler and Koch Upper Receiver Threaded Piston Guide for HK MR556 and HK416 Compatible With: HK416, MR556 M27HKP-02640$19.95 -
HK416, MR556 Ejector Port Cover Pin
H&K Heckler & Koch
$19.95Heckler and Koch Ejector Port Cover Axle Pin for HK416 and HK MR556 Compatible With: HK416, MR556HKP-02661$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 -
HK45, P30, P30L, P30SK Magazine Release
H&K Heckler & Koch
$15.95Heckler and Koch Magazine Release for HK45 and HK P30 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 -
HK416, MR556, HK417, MR762 Forward Assist Plunger Spring
H&K Heckler & Koch
$5.95Heckler and Koch's Forward Assist Plunger Spring for HK416, MR556, HK417, MR762 New HK German manufacture. Compatible With: HK416, MR556 HK417, MR762 HK G28 HK M27HKP-02537$5.95 -
HK MP5K, SP89 Receiver Flat with Weldment Set
HKP HK Parts
$239.95HKP - MP5K, SP89 Receiver Flat With Weldment Set New MP5K receiver flat and weldment set combined for the best complete build option on the market. Made by the original German tool and die maker of the LSC receiver flat utilizing factory original German...HKP-20882$239.95 -
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