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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  • New - H&K MR762 A4/417 Magazine Catch - HKP-21961 HK417, MR762A4 Magazine Catch
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    HK417, MR762A4 Magazine Catch

    H&K Heckler & Koch

    $99.95
    H&K MR762 A4/417 Magazine Catch German-made magazine catch for MR762 A4 and HK417. Compatible With: HK MR762 A1/A4 HK417  
    HKP-21961
    $99.95
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    $99.95
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  • New - H&K HK MR556 A4 Complete Upper w F/A & Ejection Door - HKP-21929 HK MR556 A4 Complete Upper - F/A & Ejection Door
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    HK MR556 A4 Complete Upper - F/A & Ejection Door

    H&K Heckler & Koch

    $845.95
    H&K HK MR556 A4 Complete Upper w F/A Ejection Door The H&K MR556 A4 Complete Upper is a superior factory assembly that comes fully equipped with a forward assist and an ejection port door, providing unparalleled reliability and precision. This...
    HKP-21929
    $845.95
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    $845.95
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  • New - H&K HK MR762/417 Upper Receiver - Incomplete - HKP-16624 HK417, MR762 Upper Receiver - Incomplete
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    HK417, MR762 Upper Receiver - Incomplete

    H&K Heckler & Koch

    $797.95
    H&K HK MR762/417 Upper Receiver - Incomplete Stripped upper receiver with threaded piston guide bushing installed. Compatible With: HK MR762 HK417
    HKP-16624
    $797.95
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    $797.95
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  • New - H&K HK MR762/417 Plate For Charging Handle - HKP-16843 HK417, MR762 Charging Handle Plate
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    HK417, MR762 Charging Handle Plate

    H&K Heckler & Koch

    $19.95
    HK MR762, HK417 Plate For Charging Handle Compatible With: HK MR762 HK417
    HKP-16843
    $19.95
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    $19.95
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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...
    HKP-18629
    $1,285.95
    Out Of Stock
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    $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
    HKP-15451
    $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
    HKP-22377
    $68.95
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    $68.95
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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: $20.95
    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...
    HKP-16768-B
    Now: $20.95
    Was: $39.95
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  • On Sale
    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

    Now: $845.95
    Was: $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...
    HKP-19798
    Now: $845.95
    Was: $999.95
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    Now: $845.95
    Was: $999.95
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  • HK MP5, HK94 Rivet for Case Deflector and Sling - Pack of 5 HK MP5, HK94 Rivet for Case Deflector and Sling - Pack of 5
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    HK MP5, HK94 Rivet for Case Deflector and Sling - Pack of 5

    LSC

    $3.95
    LSC 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
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    $3.95
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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...
    HKP-99349
    $24.95
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    $24.95
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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...
    HKP-22424
    $2,449.95
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    $2,449.95
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