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
HK416, MR556 Buffer Tube - OTB - BLEMISHED
H&K Heckler & Koch
Now: $108.71Was: $199.95H&K HK416, MR556 OTB Buffer Tube - BLEMISHED ONLY 2 UNITS AVAILABLE - AS PICTURED COSMETICALLY BLEMISHED PARTS ARE FULLY FUNCTIONAL AND SOLD AS IS. THIS PART IS NOT ELIGIBLE FOR RETURN. ALL BLEMISHED PART SALES ARE FINAL. Genuine German HK417...Now: $108.71Was: $199.95 -
On Sale
HK417, MR762 Extension Nut - Buffer Tube - Castle Receiver - BLEMISHED
H&K Heckler & Koch
Now: $18.71Was: $39.95H&K HK MR762/417 Castle Receiver Extension Nut For Buffer Tube - Black - BLEMISHED ONLY 2 UNITS AVAILABLE - AS PICTURED COSMETICALLY BLEMISHED PARTS ARE FULLY FUNCTIONAL AND SOLD AS IS. THIS PART IS NOT ELIGIBLE FOR RETURN. ALL BLEMISHED PART SALES...Now: $18.71Was: $39.95 -
On Sale
HK MP5 Receiver Flat - 9mm - no Sling Clip
HKP HK Parts
Now: $151.96Was: $189.95HKP HK MP5 9mm Receiver Flat w/o Sling Clip The MP5 9mm receiver flat serves as the foundation for custom MP5 builds. This version does not include a sling clip cutout, offering flexibility for customization. Precision-engineered for compatibility with...Now: $151.96Was: $189.95 -
On Sale
HK417, MR762 Latch Spring - Charging Handle
H&K Heckler & Koch
Now: $8.96Was: $9.95H&K HK MR762/417 Charging Handle Latch Spring This is the charging handle release latch spring. Compatible With: HK MR762 HK 417Now: $8.96Was: $9.95 -
Out Of StockOn Sale
HK33, HK53, HK93 Rear Receiver Section
H&K Heckler & Koch
Now: $71.95Was: $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.Now: $71.95Was: $79.95 -
HK MR762 A4 Upper Receiver Kit - 16"
H&K Heckler & Koch
$2,449.95HK UPPER RECEIVER KIT MR762 A4 - 16" The MR762 A4 upper kit contains a complete upper receiver and barrel assembly. The closed system design significantly reduces malfunctions typically associated with direct-impingement gas systems, as hot carbon...$2,449.95 -
On Sale
SIG Sauer / Phase 5 Hex Buffer Tube for AR-15 Pistols - 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 IS. THIS PART IS NOT ELIGIBLE FOR RETURN. ALL BLEMISHED PART SALES ARE FINAL. This buffer...Now: $14.96Was: $44.95 -
On Sale
HK416, HK MR556 Receiver End Plate - BLEMISHED
Now: $7.95Was: $19.95HK MR556/416 Receiver End Plate - BLEMISHED CONDITION MAY VARY - SEE PHOTOS 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. Aftermarket...Now: $7.95Was: $19.95 -
On Sale
HK MP5 Trunnion 10mm / .40 S&W - Factory - USED
H&K Heckler & Koch
Now: $223.46Was: $549.95H&K MP5 40/10 Factory Trunnion - USED ONLY 1 UNIT AVAILABLE - AS PICTURED Used genuine German trunnion with round guides. Compatible With: HK MP5 40/10 THIS CLOSEOUT PART IS NOT ELIGIBLE FOR RETURN, REFUND, OR EXCHANGE. SALE IS FINAL.Now: $223.46Was: $549.95 -
On Sale
HK21E, HK23E Left Receiver Reinforcement Rail Weldment
H&K Heckler & Koch
Now: $13.46Was: $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 HK23E build. Compatible With: HK21E HK23ENow: $13.46Was: $14.95 -
Out Of StockOn Sale
HK416, MR556 Upper Conversion Kit - Threaded 1/2x28, - 5.56x45 / .223
HKP HK Parts
Now: $559.96Was: $699.95H&K MR556 & HK416 (5.56x45/.223) Upper Conversion Kit - Threaded 1/2x28 Finally an answer for all of those that have been wanting a 14.5" upper for an HK416 or MR556. This conversion kit adds an upper or a barrel option for your MR556, CR556...Now: $559.96Was: $699.95 -
Out Of StockOn Sale
HK416, MR556 Upper 9" 416C Style Conversion Kit
HKP HK Parts
Now: $719.96Was: $899.95MR556 & HK416 Upper Conversion Kit - 9" - 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 9" barrel conversion kit for 416 or MR556. Each conversion kit upper or barrel...Now: $719.96Was: $899.95