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 MP5, MP5K, MKE AP5, AP5-P Case Deflector - 9mm Receivers HK MP5, MP5K, MKE AP5, AP5-P Case Deflector - 9mm Receivers

    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...
    HKP-99349
    $24.95
    Qty in Cart: 0
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    $24.95
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  • HK23E, HK21E Rear Sight Base HK23E, HK21E Rear Sight Base

    HK23E, HK21E Rear Sight Base

    H&K Heckler & Koch

    $193.95
    Heckler and Koch Rear Sight Base HK21E and HK23E  Genuine HK German rear site base.  Req
    HKP-21508
    $193.95
    Qty in Cart: 0
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    $193.95
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  • New - H&K HK MR556/MR223 A5 Incomplete Upper Receiver - Black - HKP-18785 HK MR556, MR223 A5 Incomplete Upper Receiver

    HK MR556, MR223 A5 Incomplete Upper Receiver

    H&K Heckler & Koch

    $489.95
    HK German Un-Assembled/Stripped HK MR556/MR223 A5 Upper Receiver Factory HK MR556 A5 upper receiver. This is the semi-auto MR556 variant. Compatible With: HK MR556
    HKP-18785
    $489.95
    Qty in Cart: 0
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    $489.95
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  • New - H&K HK MR556/416 E1 Incomplete Charging Handle - Black - HKP-17540 HK416 E1, MR556 Charging Handle - Incomplete

    HK416 E1, MR556 Charging Handle - Incomplete

    H&K Heckler & Koch

    $109.95
    HK MR556, HK 416 E1/E2 Charging Handle - Incomplete New HK German manufactured HK MR556, HK 416. A great item to have on hand in the event of breakage or high wear. Compatible With: HK MR556<
    HKP-17540
    $109.95
    Qty in Cart: 0
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    $109.95
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  • HK MR762 A4 Upper Receiver Kit - 16" HK MR762 A4 Upper Receiver Kit - 16"

    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...
    HKP-22424
    $2,449.95
    Qty in Cart: 0
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    $2,449.95
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  • Used - HK91, G3, HK33, HK53, HK93 Anti-Rattle Mag Release - USED - HKP-22061 HK91, G3, HK33, HK53, HK93 Paddle Magazine Release - Anti-Rattle - USED

    HK91, G3, HK33, HK53, HK93 Paddle Magazine Release - Anti-Rattle - USED

    H&K Heckler & Koch

    $42.95
    Heckler and Koch Anti Rattle Paddle Magazine Release for HK91, HK G3s and HK33, HK53, HK93 - USED This is a used German anti-rattle paddle mag release for installation on all Heckler and Koch...
    HKP-22061
    $42.95
    Qty in Cart: 0
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    $42.95
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  • On Sale
    Used - HK G3 - FMP Early Type Demilled Front End - HKP-20845 HK G3 - FMP Early Type Demilled Front End

    HK G3 - FMP Early Type Demilled Front End

    FMP HK CONTRACT

    Now: $63.72
    Was: $99.95
    HK G3 - FMP Early Type Demilled Front End Early style G3 front end with no hanger. These are the perfect option for those doing custom builds. Good condition over all. Includes: Cocking tube<
    HKP-20845
    Now: $63.72
    Was: $99.95
    Qty in Cart: 0
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    Now: $63.72
    Was: $99.95
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  • New - Tommy Built UMP Buffer Tube Adapter - HKP-19967 Tommy Built UMP Buffer Tube Adapter

    Tommy Built UMP Buffer Tube Adapter

    $249.95
    Tommy Built UMP Buffer Tube Adapter UMP hinge with Buffer Tube Mount for adapting an AR style Mil spec brace or stock. Constructed of nylon and has 6 adjustable positions. Adapter only- stocks in the...
    HKP-19967
    $249.95
    Qty in Cart: 0
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    $249.95
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  • Out Of Stock
    New - MM HK PSG1/MSG90/91/G3 (7.62x51/.308) T-Rail Reinforcement Set For Receiver - HKP-00236

    HK91, G3, PSG1, MSG90 T-Rail Reinforcement Set for Receiver

    Michaels Machines

    $299.95
    HK Receiver Reinforcement T-Rail Set For Left and Right Sides T-rails are used to strengthen HK receivers or for custom builds. These are the finest T-rails available on the market. Made from...
    HKP-00236
    $299.95
    Qty in Cart: 0
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    $299.95
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  • Out Of Stock
    New - HKP MP5, 94 Trunnion 9mm - USA - HKP-17934 HK MP5, HK94 Trunnion - 9mm - USA

    HK MP5, HK94 Trunnion - 9mm - USA

    HKP HK Parts

    $54.95
    HKP MP5, 94 Trunnion 9mm - USA US made to exact factory HK specifications for the HK MP5, 94 type builds. Machined completely from ordnance grade steel and heat treated to factory specs. These are...
    HKP-17934
    $54.95
    Qty in Cart: 0
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    $54.95
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  • HK MP5, AP5 Trunnion - 9mm HK MP5, AP5 Trunnion - 9mm

    HK MP5, AP5 Trunnion - 9mm

    MKE

    $64.95
    HK MP5 Trunnion  Made to exact factory HK specifications for the HK MP5K type builds. Machined to HK spec making the install painless and hassle free. Compatible With: MP5
    HKP-22523
    $64.95
    Qty in Cart: 0
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    $64.95
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