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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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 -
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 -
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 -
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 -
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 -
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 -
HK MP5, AP5 Trunnion - 9mm
MKE
$64.95HK MP5 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: MP5 SP5 In spec clonesHKP-22523$64.95 -
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: MP5K In spec clonesHKP-22522$79.95 -
On Sale
HK UMP Paddle Mag Release - Extended - BLEMISHED
HKP HK Parts
Now: $24.95Was: $34.95HK UMP Paddle Mag Release - Extended - 9mm / .40 S&W / .45 ACP - BLEMISHED COSMETICALLY BLEMISHED PARTS ARE FULLY FUNCTIONAL AND SOLD AS IS. THIS PART IS NOT ELIGIBLE FOR RETURN. ALL BLEMISHED PART SALES ARE FINAL. Billeted alloy UMP magazine release...HKP-17919-BNow: $24.95Was: $34.95