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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  • HK UMP Paddle Magazine Release - Extended HK UMP Paddle Magazine Release - Extended
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    HK UMP Paddle Magazine Release - Extended

    HKP HK Parts

    $34.95
    HKP HK Parts Extended Paddle Magazine Release for HK UMP 9mm, .40 S&W, .45 ACP Billeted alloy UMP magazine release. This is a very common repair and replacement part as they are fairly easy to break on the UMP lower. With this new metal mag release...
    HKP-17919
    $34.95
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  • New - H&K 91/93/33/53/G3 (5.56/.223) & (7.62x51/.308) Anti-Rattle Mag Release - HKP-01126 HK33, HK53, HK93, HK91, G3 Paddle Magazine Release - Anti-Rattle
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    HK33, HK53, HK93, HK91, G3 Paddle Magazine Release - Anti-Rattle

    H&K Heckler & Koch

    $64.95
    Heckler and Koch Anti Rattle Paddle Magazine Release This item is a new HK German genuine part not used or surplus for installation on all HK .223 and .308 HK rifles. This is the highly desired anti-rattle-style paddle mag release. Compatible...
    HKP-01126
    $64.95
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  • HK MR762 A4 Upper Receiver Kit - 13" HK MR762 A4 Upper Receiver Kit - 13"
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    HK MR762 A4 Upper Receiver Kit - 13"

    H&K Heckler & Koch

    $2,499.95
    HK MR762 A4 Upper Receiver Kit - 13" The MR762 A4 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 fouling and...
    HKP-22399
    $2,499.95
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  • On Sale
    New - HK MP5K Trunnion - Gunsmith Special - HKP-99090 HK MP5K Trunnion - Gunsmith Special
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    HK MP5K Trunnion - Gunsmith Special

    USA

    Now: $24.95
    Was: $54.95
    HK MP5K Trunnion - Gunsmith Special US made HK MP5 trunnions sold as-is. Will require work before being functional. We recommend the work be performed by a professional gunsmith. The condition will vary from part-to-part vs. the pictured unit. Compatible...
    HKP-99090
    Now: $24.95
    Was: $54.95
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  • New - H&K USC (.45 ACP) Carbine Mag Release Axle - HKP-02584
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    HK USC Magazine Release Axle

    H&K Heckler & Koch

    $18.95
    Heckler and Koch .45 ACP Magazine Release Axle for HK USC Replacement magazine release axle for HK USC .45 ACP platforms. This component is commonly replaced due to wear or breakage and may also be required when configuring compliant magazine release...
    HKP-02584
    $18.95
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  • Out Of Stock
    New - HK33, HK53, HK93 (5.56/.223) Magazine Catch - Latest Design - HKP-01059

    HK33, HK53, HK93 Magazine Catch - Latest Design

    H&K Heckler & Koch

    $49.95
    Heckler and Koch German Factory Magazine Catch for HK33, HK53, HK93 New HK German HK33, HK53, and HK93 mag catch for magazine release.  Compatible With: HK33, HK53, HK93 HK33K Clone or other custom builds
    HKP-01059
    $49.95
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  • On Sale
    New - H&K HK416A1 10.4" Upper Receiver Kit - AI Date Code (2008) - PD Trade-In - HKP-22245 H&K HK 416 10.4 - AI Upper H&K Heckler & Koch HKP-22245
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    HK416 A1 Upper Receiver - 10.4"

    H&K Heckler & Koch

    Now: $2,999.95
    Was: $3,499.95
    HK416 10.4" Complete Upper Receiver Features: Factory German 10.4" length 2008 date coded   P.D. trade-in, de-serialized during the de-milling process.  Finish your build with a matching lower from STS Tactical. Compatible With: HK416
    HKP-22245
    Now: $2,999.95
    Was: $3,499.95
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  • New - H&K HK MR762/417 Charging Handle Pin - HKP-16754
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    HK417, MR762 Charging Handle Pin

    H&K Heckler & Koch

    $6.95
    H&K HK MR762/417 Charging Handle Pin HK MR762 & HK 417 Clamping Sleeve for plate on charging handle. There are two of these pins used on the charging handle. Compatible With: HK MR762 HK 417
    HKP-16754
    $6.95
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  • Out Of Stock
    New - MM HK 21 (7.62x51/.308) Factory Style T- Rail Set - HKP-00823 HK21 T-Rail Set - Factory Style

    HK21 T-Rail Set - Factory Style

    Michaels Machines

    $275.00
    Michael's Machines HK 21 (7.62x51/.308) Factory Style T-Rail Set HK21 US-made rails for all HK21 builds. This is similar to the rails above, only prepped/cut for the HK21 feed mechanism.  
    HKP-00823
    $275.00
    Out Of Stock
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  • Out Of Stock
    New - H&K HK MR762/417 Cylindrical Pin For Stop Pin - HKP-16619

    HK417, MR762 Cylindrical Pin for Stop Pin

    H&K Heckler & Koch

    $9.95
    H&K HK MR762/417 Cylindrical Pin For Stop Pin HK 2x18 mm pin designed for use with the rear take down pin detent and spring. Compatible With: HK MR762 HK 417
    HKP-16619
    $9.95
    Out Of Stock
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  • New - H&K G36 (5.56/.223) Cocking Handle Bushing - HKP-01869
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    HK G36 Cocking Handle Bushing

    H&K Heckler & Koch

    $9.95
    HK German G36 Cocking Handle Bushing
    HKP-01869
    $9.95
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  • New - HKP MP5K 40/10 Receiver Flat - HKP-18033 HK MP5K Receiver Flat - .40 S&W, 10mm
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    HK MP5K Receiver Flat - .40 S&W, 10mm

    HKP HK Parts

    $199.95
    MP5K-40, MP5K-10 Receiver Flat - USA Receiver Flat for use with a MP5K-40 or MP5K-10mm build. Please note: This is for the flat as picture no weldments are included. ***This US made receiver flat counts as one required 922r compliant part***
    HKP-18033
    $199.95
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