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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MM HK PSG1/21E/23E Forward Complete Assist Assembly
Michaels Machines
$779.95MM HK PSG1/21E/23E Forward Complete Assist Assembly Michael's Machines US-made complete forward assembly or your HK PSG1, MSG90, HK21E/23E. A great option for a build now that the factory units are no longer available. Available exclusively...$779.95 -
HK MP5K Receiver Flat - 10mm / .40 S&W -
HKP HK Parts
$199.95MP5K-40, MP5K-10 Receiver Flat - USA Receiver Flat for use with a MP5K-40 or MP5K-10mm build. Please note: This is for the flat as picture no weldments are included. ***This US made receiver flat counts as one required 922r compliant part***$199.95 -
HK417, MR762 Cylindrical Pin for Stop Pin
H&K Heckler & Koch
$9.95H&K HK MR762/417 Cylindrical Pin For Stop Pin HK 2x18 mm pin designed for use with the rear take down pin detent and spring. Compatible With: HK MR762 HK 417$9.95 -
HK417, MR762 Takedown Pin - Front - A4 Style
H&K Heckler & Koch
$40.95H&K MR762 A4 Receiver Front Takedown Pin German-made factory pivot pin for the MR762 A4. Will work with A1 models as well. Compatible With: HK MR762 A1 and A4 HK417$40.95 -
$9.95 -
HK416 A5 Stripped Upper Receiver - RAL8000
H&K Heckler & Koch
$1,559.95HK German Un-Assembled - Stripped HK416 A5 Upper Receiver - RAL 8K Brand new factory German RAL 8000 HK416A5 upper receiver. Compatible With: HK416 HK MR556 HK MR223 Looking for a matching lower for your build? STS416 A5 LOWER - Specialized...$1,559.95 -
HK Receiver Flat Bending Set Jig - RENTAL
HKP HK Parts
$99.95Flat Bending Jig Set For All HK Style Receiver Flats - RENTAL Receiver flat bending jig RENTAL for all HK receiver flats. Our rental jigs are crafted in the US from billeted steel and include the latest revisions with proper dowel spacing for the...$99.95 -
On Sale
HK MP5 Trunnion - Gunsmith Special
USA
Now: $24.95Was: $54.95HK MP5 Trunnion - Gunsmith Special US made HK MP5 trunnions sold as-is. Will require work before being functional. We recommend the work be performed by a professional gunsmith. The condition will vary from part-to-part vs. the pictured unit. Compatible...Now: $24.95Was: $54.95 -
On Sale
HK416, MR556 Receiver End Plate - BLEMISHED
H&K Heckler & Koch
Now: $11.21Was: $24.95H&K HK MR556/416 Receiver End Plate - BLEMISHED INSTALLATION MARKS. COSMETICALLY BLEMISHED PARTS ARE FULLY FUNCTIONAL AND SOLD AS IS. THIS PART IS NOT ELIGIBLE FOR RETURN. ALL BLEMISHED PART SALES ARE FINAL. New HK German manufacture. Compatible...Now: $11.21Was: $24.95 -
Out Of Stock
HK416 Upper Receiver
HKP HK Parts
$489.95US Made Complete HK 416, MR556 Style Upper Receiver New US made HK416/MR556 style upper receiver. Includes: Upper receiver Forward assist assembly Ejection port door assembly Piston guide Compatible With: HK MR556 HK MR223 HK 416 Need a...$489.95 -
HK21E Feed Mechanism - Complete - 7.62 / .308
H&K Heckler & Koch
$22,495.95HK21E Feed Mechanism Complete - German HK - DM1 Links New genuine HK date-coded and marked 21E complete feed mechanism. These are the last of the genuine feed mechs available and due to the HK officially discontinuing the 21E, no additional factory units...$22,495.95 -
HK416, MR556, AR-15 Commercial Buffer Tube Kit
HKP HK Parts
$47.95AR-15 Commercial Buffer Tube Kit Compatible With: HK MR556 & 416 All AR-15 style platforms Includes: Made with T7 7075 aircraft-grade aluminum Made in the USA with a polished inside tube Mil-Spec triple hard coat Teflon anodized...$47.95