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 - 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...
    HKP-21828
    $189.95
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    $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.
    HKP-16481
    $79.95
    Out Of Stock
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    $79.95
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  • Out Of Stock
    On Sale
    New - H&K 416 Front Takedown Pin - HKP-21862 HK416, MR556 Takedown Pin - Front - A4 Style - BLEMISHED

    HK416, MR556 Takedown Pin - Front - A4 Style - BLEMISHED

    H&K Heckler & Koch

    Now: $15.95
    Was: $26.95
    HK416, MR556 Takedown Pin - Front - A4 Style - BLEMISHED COSMETICALLY BLEMISHED PARTS ARE FULLY FUNCTIONAL AND SOLD AS IS. THIS PART IS NOT ELIGIBLE FOR RETURN. ALL BLEMISHED PART SALES ARE FINAL. The HK416 front takedown pin is a German-made component...
    HKP-21862-B
    Now: $15.95
    Was: $26.95
    Out Of Stock
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  • On Sale
    HK VP9, VP40 Enhanced Magazine Release - Red- BLEMISHED
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    HK VP9, VP40 Enhanced Magazine Release - Red- BLEMISHED

    HKP HK Parts

    Now: $36.95
    Was: $49.95
    HK VP9, VP40 Enhanced Magazine Release - Red- BLEMISHED COSMETICALLY BLEMISHED PARTS ARE FULLY FUNCTIONAL AND SOLD AS IS. THIS PART IS NOT ELIGIBLE FOR RETURN. ALL BLEMISHED PART SALES ARE FINAL. The oversized magazine release increases the overall...
    HKP-21099-RE-B
    Now: $36.95
    Was: $49.95
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    Now: $36.95
    Was: $49.95
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  • On Sale
    HK91, G3 Mag Release Set - USED HK91, G3 Mag Release Set - USED
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    HK91, G3 Mag Release Set - USED

    H&K Heckler & Koch

    Now: $19.95
    Was: $34.95
    HK91, G3 Mag Release Set - USED ONLY 1 UNIT AVAILABLE - AS PICTURED USED PARTS ARE SOLD AS IS. THIS PART IS NOT ELIGIBLE FOR RETURN. ALL USED PART SALES ARE FINAL. This magazine catch set consists of 4 pieces and is HK-manufactured. Includes: Magazine...
    HKP-00929-USED
    Now: $19.95
    Was: $34.95
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    Was: $34.95
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  • On Sale
    HK UMP Paddle Mag Release - Extended - BLEMISHED HK UMP Paddle Mag Release - Extended - BLEMISHED
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    HK UMP Paddle Mag Release - Extended - BLEMISHED

    HKP HK Parts

    Now: $24.95
    Was: $34.95
    HK 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-B
    Now: $24.95
    Was: $34.95
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    Now: $24.95
    Was: $34.95
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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
    HKP-99348
    $32.95
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    $32.95
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  • On Sale
    Used - H&K MP5 40/10 Factory Trunnion - USED - HKP-99173 HK MP5 Trunnion 10mm / .40 S&W - Factory - USED
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    HK MP5 Trunnion 10mm / .40 S&W - Factory - USED

    H&K Heckler & Koch

    Now: $297.95
    Was: $549.95
    H&K MP5 40/10 Factory Trunnion - USED ONLY 1 UNIT AVAILABLE - AS PICTURED Used genuine German trunnion with round guides. Compatible With: HK MP5 40/10 THIS CLOSEOUT PART IS NOT ELIGIBLE FOR RETURN, REFUND, OR EXCHANGE.  SALE IS FINAL.
    HKP-99173
    Now: $297.95
    Was: $549.95
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    Now: $297.95
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  • Out Of Stock
    New - HK UMP Paddle Mag Release Complete Assembly - HKP-19499 HK UMP Paddle Mag Release Complete Assembly

    HK UMP Paddle Mag Release Complete Assembly

    $19.95
    UMP Paddle Magazine Release - US Made - Assembly Complete New UMP Mag release. This is a very common repair & replacement part as they are fairly easy to break on the UMP lower. Simple & easy to install no gunsmith needed or required. Compatible...
    HKP-19499
    $19.95
    Out Of Stock
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    $19.95
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  • Out Of Stock
    New - H&K MR556 & HK416 (5.56x45/.223) Upper Conversion Kit - Threaded 1/2x28 - HKP-17877 HK416, MR556 Upper Conversion Kit - Threaded 1/2x28, - 5.56x45 / .223

    HK416, MR556 Upper Conversion Kit - Threaded 1/2x28, - 5.56x45 / .223

    HKP HK Parts

    $699.95
    H&K MR556 & HK416 (5.56x45/.223) Upper Conversion Kit - Threaded 1/2x28 Finally an answer for all of those that have been wanting a 14.5" upper for an HK416 or MR556. This conversion kit adds an upper or a barrel option for your MR556, CR556...
    HKP-17877
    $699.95
    Out Of Stock
    Qty in Cart: 0
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    $699.95
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  • Out Of Stock
    New - HKP HK USC (.45 ACP) Carbine Mag Release - Extended - HKP-17918

    HK USC Magazine Release - Extended - .45 ACP

    HKP HK Parts

    $24.95
    HK USC Alloy Mag Release - Extended Billeted alloy USC magazine release. This is a very common repair & replacement part as they are fairly easy to break on the USC lower. With this new metal mag release you get more surface area as well as a much...
    HKP-17918
    $24.95
    Out Of Stock
    Qty in Cart: 0
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    $24.95
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  • Out Of Stock
    Used - H&K UMP (.40 S&W/.45 ACP/9mm) Demilled Rear Receiver Section - HKP-01659 HK UMP (.40 S&W/.45 ACP/9mm) Demilled Rear Receiver Section

    HK UMP (.40 S&W/.45 ACP/9mm) Demilled Rear Receiver Section

    H&K Heckler & Koch

    $0.00
    HK UMP Demilled Receiver Section This is a demilled factory HK UMP rear receiver section that is perfect for the new Tom Bostic USC-UMP conversions. This section is the perfect length in order to do the USC/UMP conversion. Last one available.
    HKP-01659
    $0.00
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    Qty in Cart: 0
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    $0.00
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