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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On Sale
HK FMP G3 Early Type De-Milled Front End - No Cocking Handle Assembly
FMP HK CONTRACT
Now: $43.96Was: $68.95HK G3 - FMP Early Type De-milled Front End - No Cocking Handle Assembly Early style G3 front end with no hanger from de-milled FMP G3 parts kits. Perfect for custom builds. Includes: CoHKP-22377Now: $43.96Was: $68.95 -
HK MR556 A4 Upper, Complete - Full Auto and Ejection Door
H&K Heckler & Koch
$845.95HK Heckler and Koch A4 Complete Upper with Full Auto Ejection Door for HK MR556 The HK MR556 A4 Complete Upper is a superior factory assembly that comes fully equipped with a forward assist and an...HKP-21929$845.95 -
On Sale
HK UMP Demilled Extended Rear Receiver Section
H&K Heckler & Koch
Now: $689.95Was: $999.95HK German Factory UMP Receiver Section - Extended Demilled factory HK UMP rear receiver section perfect for a USC-UMP conversion. With the folding stock attachment point intact right in front of the...HKP-19798Now: $689.95Was: $999.95 -
HK417, MR762 Upper Receiver - Incomplete
H&K Heckler & Koch
$797.95H&K HK MR762/417 Upper Receiver - Incomplete Stripped upper receiver with threaded piston guide bushing installed. Compatible With: HK MR762HKP-16624$797.95 -
HK MP5K, AP5-P Trunnion - 9mm
MKE
$79.95HK MP5K Trunnion Made to exact factory HK specifications for the HK MP5K type builds. Machined to HK spec making the install painless and hassle free. Compatible With: MP5KHKP-22522$79.95 -
HK417, MR762 Charging Handle Plate
H&K Heckler & Koch
$19.95HK MR762, HK417 Plate For Charging Handle Compatible With: HK MR762 HK417HKP-16843$19.95 -
Out Of Stock
HK416, MR556 Upper 8" 416C Style Conversion Kit
HKP HK Parts
$1,285.95Upper Conversion Kit for HK416 and MR556 8 inch barrel - HK 416C Style Finally an answer for all of those that have been wanting as close to the original, rare unicorn of a find HK 416C 8" barrel...HKP-18629$1,285.95 -
HK21 Barrel Grip Axle Pin
H&K Heckler & Koch
$9.95HK21 Barrel Grip Axle Pin Factory axle pin for HK21 barrel handle release levers.HKP-15451$9.95 -
On Sale
AR15 Buffer Tube - Hex - 7.5" - BLEMISHED
Sig Sauer
Now: $14.96Was: $44.95SIG Sauer Phase 5 Hex Buffer Tube for AR-15 Pistols - BLEMISHED ONLY 1 UNIT AVAILABLE - AS PICTURED COSMETICALLY BLEMISHED PARTS ARE FULLY FUNCTIONAL AND SOLD AS IHKP-99304Now: $14.96Was: $44.95 -
HK21E, HK23E Left Receiver Reinforcement Rail Weldment
H&K Heckler & Koch
$14.95H&K 21E/23E Left Receiver Reinforcement Rail Weldment Genuine German-made weldment for left-side receiver reinforcement rail. Precision-machined using the correct steel and milling for you HK21E or...HKP-21907$14.95 -
Out Of Stock
HK33, HK53, HK93 Rear Receiver Section
H&K Heckler & Koch
$79.95H&K 93/53/33 (5.56/.223) Rear Receiver Section Each rear receiver section is from a factory German HK 33/53 that was demilled and includes the welded on rear sight base and push pin bushing intact.HKP-16481$79.95 -
On Sale
HK German Bayonet Adapter Without Hardware - Incomplete - USED
H&K Heckler & Koch
Now: $74.96Was: $159.95HK German Bayonet Adapter Without Hardware - Incomplete - USED SOLD INDIVIDUALLY - VARYING CONDITION SHOWN <HKP-00021-BNow: $74.96Was: $159.95