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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  • On Sale
    New - MI HK MP5 1913 End Plate Adapter - HKP-21493 HK MP5 1913 End Plate Adapter
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    HK MP5 1913 End Plate Adapter

    MI Midwest Industries

    Now: $75.95
    Was: $89.95
    MI HK MP5 1913 End Plate Adapter The Midwest Industries Picatinny end plate adapter opens up your stock and brace options to a myriad of off-the-shelf possibilities. The adapter installs in the same manner as the factory end cap with a single push pin...
    HKP-21493
    Now: $75.95
    Was: $89.95
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  • New - H&K SP5K 9mm Drop In Paddle Mag Release Upgrade Kit - HKP-18082 HK SP5K 9mm Drop In Paddle Mag Release Upgrade Kit
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    HK SP5K 9mm Drop In Paddle Mag Release Upgrade Kit

    H&K Heckler & Koch

    $129.95
    HKP HK Parts and Heckler and Koch Anti-Rattle Roller Tipped Paddle Magazine Release Kit  No modifications, no refinishing...complete drop-in kit included New HK German and USA made paddle mag release kit for the HK SP5K. This kit will allow any...
    HKP-18082
    $129.95
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  • Out Of Stock
    New - H&K HK MR556/416 Receiver End Plate - HKP-16603 HK416, MR556 Receiver End Plate

    HK416, MR556 Receiver End Plate

    H&K Heckler & Koch

    $24.95
    HK 416, MR556 End Plate For Receiver & Buffer Tube New HK German manufacture. Compatible With: HK MR556 & HK 416 upper receiver/buffer tubes
    HKP-16603
    $24.95
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    New - H&K HK MR556 Front Lower Receiver Locking Pin - HKP-02663 HK416, MR556 Takedown Pin - Front - A1 Style

    HK416, MR556 Takedown Pin - Front - A1 Style

    H&K Heckler & Koch

    $64.95
    H&K HK MR556 Front Lower Receiver Locking Pin With Spring Loaded Detent This part is the front (large) takedown pin with ball detent and locking mechanism installed. The idea behind this type of system is to decrease the movement of the upper and...
    HKP-02663
    $64.95
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  • On Sale
    New - GSG9 HK SL8, HK G36 Magazine Release Axle Pin - HKP-18255 HK SL8, G36 Magazine Release Axle Pin
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    HK SL8, G36 Magazine Release Axle Pin

    GSG9

    Now: $8.95
    Was: $10.95
    GSG9 Magazine Release Axle - USA made for HK G36 and HK SL8 Mag release axle for all G36 and SL8 models. A must-have spare part. Made in the USA. Compatible With: G36 G36K SL8 Other custom G36 type builds
    HKP-18255
    Now: $8.95
    Was: $10.95
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  • On Sale
    New - LSC/PTR Receiver Flat- MP5 9mm - HKP-01431 HK MP5 Receiver Flat- 9mm
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    HK MP5 Receiver Flat- 9mm

    LSC

    Now: $215.95
    Was: $239.95
    MP5 Receiver Flat - PTR/LSC New PTR 9mm Receiver Flat made on the original LSC tooling. This flat is considered by many to be the most sought-after HK flat available on the market and perfect for that HK custom build. This item is not considered an FFL...
    HKP-01431
    Now: $215.95
    Was: $239.95
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  • New - H&K HK MR556 Incomplete Upper Receiver - HKP-02615 HK MR556 Incomplete Upper Receiver
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    HK MR556 Incomplete Upper Receiver

    H&K Heckler & Koch

    $440.95
    HK German Stripped HK MR556 Upper Receiver New factory German incomplete and unmarked MR556 upper receiver. Compatible With: HK MR556 HK MR223 HK 416 Do you need a matching lower for your build?  STS416 A5 LOWER - Specialized Tactical...
    HKP-02615
    $440.95
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  • Out Of Stock
    New - H&K MP5 40/10 Case Deflector - HKP-02170 HK SP5 Case Deflector - 9mm, 10mm, .40 S&W

    HK SP5 Case Deflector - 9mm, 10mm, .40 S&W

    H&K Heckler & Koch

    $49.95
    Heckler and Koch Case Deflector for 9mm, 10mm, and .40 S&W HK SP5   Factory HK case deflector for the SP5 platform chambered in 9mm, 10mm, and .40 S&W.   Compatible With: SP5  
    HKP-02170
    $49.95
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  • On Sale
    New - Tac Latch - PTR Spec - HKP-17611 PTR Spec Tac Latch
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    PTR Spec Tac Latch

    Other

    Now: $62.95
    Was: $69.95
    Tac Latch (latest Generation) PTR Spec - PTR .308 Firearms The new updated style of Tac latch is made specifically for the PTR 91 .308 receiver and will require very little modification to the firearm for installation. A major overhaul of the existing...
    HKP-17611
    Now: $62.95
    Was: $69.95
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  • New - H&K HK MR556/MR762/416 Forward Assist Assembly - HKP-16528 HK416, MR556, MR762 Forward Assist Assembly, Complete
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    HK416, MR556, MR762 Forward Assist Assembly, Complete

    H&K Heckler & Koch

    $74.95
    H&K Heckler and Koch Forward Assist Assembly for HK416, HK MR556, and HK MR762  H&K Germany factory HK MR556 and HK416 forward assist assembly complete. Compatible With: HK 416, MR556 HK MR762
    HKP-16528
    $74.95
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  • New - H&K HK MR556/MR762/416/417 Forward Assist Plunger Spring - HKP-02537
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    HK416, MR556, HK417, MR762 Forward Assist Plunger Spring

    H&K Heckler & Koch

    $5.95
    Heckler and Koch's Forward Assist Plunger Spring for HK416, MR556, HK417, MR762  New HK German manufacture. Compatible With: HK416, MR556 HK417, MR762 HK G28 HK M27
    HKP-02537
    $5.95
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  • New - H&K HK416/MR556 Magazine Catch - HKP-15458 HK416, MR556 Magazine Catch
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    HK416, MR556 Magazine Catch

    H&K Heckler & Koch

    $59.95
    Heckler and Koch Magazine Catch for HK416 and HK MR556 New HK German manufacture magazine catch for the HK 416 and MR556 family of firearms. Compatible With: HK416, MR556
    HKP-15458
    $59.95
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