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
HK417, MR762 Extension Nut - Buffer Tube - Castle Receiver - BLEMISHED
H&K Heckler & Koch
Now: $24.95Was: $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...HKP-16768-BNow: $24.95Was: $39.95 -
HK UMP Demilled Extended Rear Receiver Section
H&K Heckler & Koch
$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 ejection port, this extended receiver section is...HKP-19798$999.95 -
HK CC9 Magazine Spring - 12 Round
H&K Heckler & Koch
$5.95Heckler and Koch 12-Round Magazine Spring for HK CC9 Genuine 12-round HK CC9 steel magazine spring. Compatible With: HK CC9HKP-22509$5.95 -
HK MP5, MP5K, MKE AP5, AP5-P Case Deflector - 9mm Receivers
MKE
$24.95MKE AP5, AP5-P, HK MP5, MP5K Case Deflector for 9mm Receivers This steel case deflector is manufactured by MKE for AP5 firearms and fits MP5-pattern 9mm receivers. It installs on the ejection-port flat of the receiver and is riveted or welded in place to...HKP-99349$24.95 -
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...HKP-22424$2,449.95 -
HK MR556, MR223 Upper Receiver - BLEMISHED
H&K Heckler & Koch
$695.95HK MR556, MR223 Upper Receiver - BLEMISHED ONLY 1 UNIT AVAILABLE - AS PICTURED MISSING FORWARD ASSIST AND GAS PISTON COSMETICALLY BLEMISHED PARTS ARE FULLY FUNCTIONAL AND SOLD AS IS. THIS PART IS NOT ELIGIBLE FOR RETURN. ALL BLEMISHED PART SALES ARE...HKP-16950-BL-B$695.95 -
On Sale
AR15 Buffer Tube - Hex - 7.5" - BLEMISHED
Sig Sauer
Now: $19.95Was: $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...HKP-99304Now: $19.95Was: $44.95 -
HK416, MR556 Enhanced Buffer Tube - Tan
H&K Heckler & Koch
$192.95Tan HK 416, MR556 OTB (over the beach) Buffer Tube, Receiver Extension - Commercial Genuine HK German-manufactured 416 & MR556 latest generation, marine environment & and over-the-beach buffer tube. Each commercial buffer tube features built-in...HKP-22086$192.95 -
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 HK23E build. Compatible With: HK21E HK23EHKP-21907$14.95 -
HK MP5 Receiver Flat - 9mm - no Sling Clip
HKP HK Parts
$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...HKP-21828$189.95 -
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 MP5 40/10 Receiver Flat - BLEMISHED
HKP HK Parts
Now: $136.95Was: $399.95HK MP5 40/10 Receiver Flat - 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. The new and latest production with the...HKP-00767-BNow: $136.95Was: $399.95