Receivers / Flats / Uppers

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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  • Out Of Stock
    New - HKP HK MR556/416 Upper 8" 416C Style Conversion Kit - HKP-18629 HK416, MR556 Upper 8" 416C Style Conversion Kit

    HK416, MR556 Upper 8" 416C Style Conversion Kit

    HKP HK Parts

    $1,285.95
    Upper 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 conversion kit for 416 or MR556. Each conversion kit...
    $1,285.95
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  • New - H&K 21 (7.62x51/.308) Axle pin - HKP-15451
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    HK21 Axle pin - 7.62x51 / .308

    H&K Heckler & Koch

    $9.95
    H&K 21 (7.62x51/.308) Axle pin 11x12mm
    $9.95
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    $9.95
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  • HK G3 - FMP Early Type Demilled Front End - No Cocking Handle Assembly FMP HK CONTRACT HKP-22377 HK G3 - FMP Early Type Demilled Front End - No Cocking Handle Assembly FMP HK CONTRACT HKP-22377
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    HK FMP G3 Early Type De-Milled Front End - No Cocking Handle Assembly

    FMP HK CONTRACT

    $68.95
    HK 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 pin
    $68.95
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  • New - H&K MR762 A4 Buffer Tube - HKP-21964 HK MR762 A4 Buffer Tube
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    HK MR762 A4 Buffer Tube

    H&K Heckler & Koch

    $95.95
    H&K MR762 A4 Buffer Tube Factory German-made buffer tube for the MR762 A4. Compatible With: HK MR762 A1/A4
    $95.95
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  • Used - H&K HK UMP Demilled Extended Rear Receiver Section - HKP-19798 HK UMP Demilled Extended Rear Receiver Section
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    HK UMP Demilled Extended Rear Receiver Section

    H&K Heckler & Koch

    $999.95
    HK 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...
    $999.95
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  • HK MR762 A4 Upper Receiver Kit - 16" HK MR762 A4 Upper Receiver Kit - 16"
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    HK MR762 A4 Upper Receiver Kit - 16"

    H&K Heckler & Koch

    $2,449.95
    HK 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
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  • On Sale
    New - H&K HK MR762/417 Castle Receiver Extension Nut For Buffer Tube - Black - BLEMISHED - HKP-16768-B HK417, MR762 Extension Nut - Buffer Tube - Castle Receiver - BLEMISHED
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    HK417, MR762 Extension Nut - Buffer Tube - Castle Receiver - BLEMISHED

    H&K Heckler & Koch

    Now: $24.95
    Was: $39.95
    H&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: $24.95
    Was: $39.95
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  • New - HKP HK MP5 9mm Receiver Flat w/o Sling Clip - HKP-21828 HK MP5 Receiver Flat - 9mm - no Sling Clip
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    HK MP5 Receiver Flat - 9mm - no Sling Clip

    HKP HK Parts

    $189.95
    HKP 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...
    $189.95
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  • Out Of Stock
    Used - H&K 93/53/33 (5.56/.223) Rear Receiver Section - HKP-16481 HK33, HK53, HK93 Rear Receiver Section

    HK33, HK53, HK93 Rear Receiver Section

    H&K Heckler & Koch

    $79.95
    H&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.
    $79.95
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  • HK MP5, MP5K, MKE AP5, AP5-P Case Deflector - 9mm Receivers HK MP5, MP5K, MKE AP5, AP5-P Case Deflector - 9mm Receivers
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    HK MP5, MP5K, MKE AP5, AP5-P Case Deflector - 9mm Receivers

    MKE

    $24.95
    MKE 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...
    $24.95
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  • HK91, G3, HK93 Anti-Rattle Mag Release HK91, G3, HK93 Anti-Rattle Mag Release
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    HK91, G3, HK93 Anti-Rattle Mag Release

    MKE

    $32.95
    MKE Anti Rattle Paddle Magazine Release Upgrade your rifle with MKE's anti-rattle style paddle mag release. Compatible With: HK G3, HK91 HK33, HK53, HK93 HK PSG1, MSG90 In-spec clones and custom builds
    $32.95
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  • HK417, MR762 Upper Receiver and Handguard - Flecktarn HK417, MR762 Upper Receiver and Handguard - Flecktarn
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    HK417, MR762 Upper Receiver and Handguard - Flecktarn

    H&K Heckler & Koch

    $1,489.95
    HK417, MR762 Upper Receiver and 13.5" Handguard - Flecktarn Factory HK MR762 matching flecktarn upper receiver and 13.5" handguard.   ONLY 3 SETS AVAILABLE AND WILL NOT BE RESTOCKED Compatible With: HK MR762 HK417  
    $1,489.95
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