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 HK MR556 Front Lower Receiver Locking Pin - HKP-02663 HK416, MR556 Takedown Pin - Front - A1 Style
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    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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  • 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

    $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
    $10.95
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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 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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  • 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

    $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
    $89.95
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  • MKE HK MP5/MP5K Magazine Release Bushing MKE HKP-22283 MKE HK MP5/MP5K Magazine Release Bushing MKE HKP-22283
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    HK MP5, HK90 Series Paddle Mag Release Bushing - Full Auto

    MKE

    $2.59
    MKE Magazine Release Bushing for HK MP5, MP5K and HK90 Firearms This part is for use in all HK90-series Heckler and Koch weapon systems and is used for installing a paddle mag release. This is not for use on semi-auto HK builds. This part is intended for...
    HKP-22283
    $2.59
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  • Out Of Stock
    New - H&K HK MR556/416 Ejection Port Cover Door Assembly - HKP-16951 HK416, MR556 Ejection Port Cover Assembly

    HK416, MR556 Ejection Port Cover Assembly

    H&K Heckler & Koch

    $89.95
    HK German HK 416, MR556 Ejection Port Cover Door Assembly Complete This is the newer polymer style cover found on the latest HK 416 and MR556's. This is the complete ejection port door assembly needed on all AR15 or MR556/HK416 models. Can also be used...
    HKP-16951
    $89.95
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  • New - Tac Latch - PTR Spec - HKP-17611 PTR Spec Tac Latch
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    PTR Spec Tac Latch

    Other

    $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
    $69.95
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  • New - MP5, HK94, MP5K, SP89 & SP5K - Tac Latch - HKP-02792 HK MP5, HK94, MP5K, SP5K Tac Latch
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    HK MP5, HK94, MP5K, SP5K Tac Latch

    Other

    $69.95
    New Tac Latch (latest Generation) Paddle Style Magazine Release For The HK94, SP89, HK SP5K Family of Firearms HK's were designed to have a quick one-handed release capability for the magazine (paddle mag release). However, the semi-auto...
    HKP-02792
    $69.95
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  • New - DTAC Picatinny Rail For HK Receivers - 15 Slot - HKP-17819 Picatinny Rail for HK Receivers - 15 Slot
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    Picatinny Rail for HK Receivers - 15 Slot

    DTAC Dakota Tactical

    $74.95
    Dakota Tactical Picatinny Rail To Weld To The Receiver Mil-Spec all steel picatinny rail in the white, relief cut for HK receivers & made for mounting scopes and optics to HK builds. This unit easily welds to the top of your HK receiver. Compatible...
    HKP-17819
    $74.95
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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

    $449.95
    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
    $449.95
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  • New - HKP HK MP5F Flat - Alternate Holes - HKP-21551 HK MP5F Receiver Flat - Alternate Holes
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    HK MP5F Receiver Flat - Alternate Holes

    HKP HK Parts

    $125.95
    HKP HK MP5F 9mm Flat - Alternate Holes MP5 receiver flat crafted by the original German tool and die maker of the LSC receiver flat using factory original German prints and specifications. This receiver features alternate holes for the correct MP5F or...
    HKP-21551
    $125.95
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