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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HK91, G3, HK91, HK33, HK53, HK93 Paddle Mag Release - Anti-Rattle - USED
H&K Heckler & Koch
$42.95H&K G3/91/93/53/33 Anti-Rattle Mag Release - USED This is a used German anti-rattle paddle mag release for installation on all H&K .223 and .308 rifles. Compatible With: HK G3/91 HK 51 HK 93/53/33 HK PSG-1 HK MSG-90 PTR91 Clones and other custom...HKP-22061$42.95 -
HK417, MR762A4 Magazine Catch
H&K Heckler & Koch
$99.95H&K MR762 A4/417 Magazine Catch German-made magazine catch for MR762 A4 and HK417. Compatible With: HK MR762 A1/A4 HK417HKP-21961$99.95 -
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 -
HK21 Axle pin - 7.62x51 / .308
H&K Heckler & Koch
$9.95H&K 21 (7.62x51/.308) Axle pin 11x12mmHKP-15451$9.95 -
HK FMP G3 Early Type De-Milled Front End - No Cocking Handle Assembly
FMP HK CONTRACT
$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: Cocking tube Trunnion Barrel pinHKP-22377$68.95 -
On Sale
HK417, MR762 Extension Nut - Buffer Tube - Castle Receiver - BLEMISHED
H&K Heckler & Koch
Now: $20.95Was: $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: $20.95Was: $39.95 -
HK MP5, HK94 Rivet for Case Deflector and Sling - Pack of 5
LSC
$3.95LSC HK MP5, HK94 Rivet for Sling Clip and Case Deflector - Pack of 5 Each case deflector, US or German-made, will require two rivets to attach the case deflector to the receiver or flat. You will need two of these for installing one case deflector...HKP-99400$3.95 -
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 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