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 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...$14.95 -
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 M27$5.95 -
HK91, G3, HK33, HK53, HK93 Contact Piece for Paddle Mag Release
H&K Heckler & Koch
$29.95HK .223/556 & 308 Contact Piece For Paddle Magazine Release German HK manufacture. The contact piece is used in the magazine release assembly for the paddle mag release. Compatible With: HK 33, 53, 93 HK G3, 91, PTR91$29.95 -
HK MP5 Receiver Flat - 9mm
HKP HK Parts
$189.95HKP HK MP5 9mm Receiver Flat New MP5 receiver flat made by the original German tool and die maker of the LSC receiver flat utilizing factory original German prints and specifications. The creator of our receiver flat has been regarded as the premier flat...$189.95 -
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...$239.95 -
HK G36 Backplate Complete w/ Recoil Assembly
USA
$84.95HK G36 Backplate Complete With Recoil Assembly New G36 Backplate with new G36/SL8 recoil buffer and recoil assembly. This assembly does include the recoil rod retaining screw. This is a great spare or replacement to have on hand. These are also required...$84.95 -
HK MP5K 9mm Trunnion
HKP HK Parts
$57.95HK MP5K Trunnion - USA US made to exact factory HK specifications for the HK MP5K type builds. Machined completely from ordnance grade steel and heat treated to factory specs. These are the best USA made trunnions on the market. Machined to HK spec...$57.95 -
HK MP5 Magazine Release Lever Spring - 10mm and .40 S&W
H&K Heckler & Koch
$9.95H&K MP5 40/10 Magazine Release Lever Spring The needed spring that fits in the mag release lever and the magwell for the MP5 40/10 series. Made in Germany and no longer offered or made. These units are the latest design with the ground ends for...$9.95 -
HK MP5, MP5K Rear Sight Base - Billeted
HKP HK Parts
$17.95Billeted MP5, MP5K Rear Sight Base - Weldment All steel HK MP5, MP5K billeted rear sight base. The most correct MP5, MP5K rear sight base available. The only billeted factory correct sight base with the factory HK German side axis grooves. If you want...$17.95 -
DTAC Picatinny Rail For HK Receivers - 13 Slot
DTAC Dakota Tactical
$74.95DTAC Picatinny Rail For HK Receivers - 13 Slot Mil-Spec all steel picatinny rail in the white, relief cut for HK receivers & made for mounting scopes and optics to HK builds. This unit easily welds to the top of your HK receiver. Compatible With: HK...$74.95 -
HK416, MR556 Ejector Port Cover Pin
H&K Heckler & Koch
$19.95HK MR556 & 416 Ejector Port Cover Pin Compatible With: HK MR556 HK 416$19.95 -
HK416A5 Stripped Upper Receiver
H&K Heckler & Koch
$489.99HK 416A5 - Stripped Upper Receiver This is the factory correct receiver for a true 416 build as it features the M16 relief cut in the bottom, rear portion of the receiver (shown in last pricture). Compatible With: HK 416 HK MR223 HK MR556 Need a...$489.99