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 - HKP HK 416C 9" Complete Upper Receiver Assembly - HKP-21042 HK416C Upper Receiver Kit - 9"

    HK416C Upper Receiver Kit - 9"

    HKP HK Parts

    Now: $2,239.96
    Was: $2,799.95
    HK416C Complete Upper Kit - 9"  Our complete 416C upper kit includes everything you need to pair with a mil-spec lower or an STS 416C lower. For that genuine look, the STS 416C lower with the correct 416C stock eyelets is as good as you can get...
    Now: $2,239.96
    Was: $2,799.95
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    Now: $2,239.96
    Was: $2,799.95
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  • On Sale
    Used - H&K HK 416/MR556 Enhanced Buffer Tube-Commercial - HKP-15424 H&K HK 416/MR556 Enhanced Buffer Tube-Commercial H&K Heckler & Koch HKP-15424
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    HK416, MR556 Buffer Tube - Enhanced - Commercial

    H&K Heckler & Koch

    Now: $224.95
    Was: $249.95
    HK 416, MR556 OTB (over the beach) Buffer Tube, Receiver Extension - Commercial: Genuine HK German manufactured 416, MR556 new style latest generation marine environment & over the beach buffer tube. Each Commercial buffer tube has built in drainage...
    Now: $224.95
    Was: $249.95
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    Now: $224.95
    Was: $249.95
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  • On Sale
    New - H&K HK MR762/417/G28 Receiver End Plate - HKP-16610 HK417, MR762, G28 Receiver End Plate
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    HK417, MR762, G28 Receiver End Plate

    H&K Heckler & Koch

    Now: $22.45
    Was: $24.95
    H&K HK MR762/417/G28 Receiver End Plate New HK German factory. Compatible With: HK MR762 HK 417 HK G28
    Now: $22.45
    Was: $24.95
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    Now: $22.45
    Was: $24.95
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  • On Sale
    New - HK G36/SL8 (5.56/.223) Cocking Handle Spring - HKP-18369 HK G36, SL8 Spring - Cocking Handle - US
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    HK G36, SL8 Spring - Cocking Handle - US

    Now: $8.96
    Was: $9.95
    G36 Cocking Handle Spring- US Made   Compatible With: G36 All variants SL8 All variants
    Now: $8.96
    Was: $9.95
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  • Used - H&K MP5 Rear Receiver Section - HKP-02167
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    HK MP5 Rear Receiver Section

    H&K Heckler & Koch

    $14.95
    H&K MP5 Rear Receiver Section HK German demilled receiver section with rear sight base as installed at the factory. MP5 & HK94 Factory HK rear sight bases (portion welded to MP5 receiver), you get the actual demilled section of an MP5 receiver...
    $14.95
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    $14.95
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  • On Sale
    New - HKP AR-15 Commercial Buffer Tube - HKP-02728
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    HK AR-15 Commercial Buffer Tube

    HKP HK Parts

    Now: $19.96
    Was: $24.95
    AR-15 Commercial Buffer Tube Compatible With: HK MR556 & 416 All AR-15 style platforms Features: Made From T7 7075 Aircraft grade aluminum Made in the USA 6 Position Each features a highly polished inside tube Black Mil-spec triple hard coat...
    Now: $19.96
    Was: $24.95
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  • On Sale
    Used - H&K MIL-SPEC 416 OTB Buffer Tube & HK E1 Stock Combo - HKP-20104 HK416 OTB E1 Stock & Buffer Tube Combo
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    HK416 OTB E1 Stock & Buffer Tube Combo

    H&K Heckler & Koch

    Now: $422.95
    Was: $469.95
    H&K MIL-SPEC 416 OTB Buffer Tube & HK E1 Stock Combo Genuine HK416 E1 Stock with the new style marine environment "over the beach" buffer tube. Buffer tube has ball bearing rollers to tighten the stock when locked in position, and helps smooth...
    Now: $422.95
    Was: $469.95
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    Now: $422.95
    Was: $469.95
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  • Out Of Stock
    New - H&K HK G28 Buffer Tube - FDE - HKP-16762 HK417, MR762, G28 Buffer Tube - FDE

    HK417, MR762, G28 Buffer Tube - FDE

    H&K Heckler & Koch

    $224.95
    HK G28 Buffer Tube / Receiver Extension- HK Tan (Ral 8000) New HK German buffer tube with the proper slot cut for use with the G28 stock. This is the factory correct part needed to get the full range and use of the G28 adjustable stock. Compatible...
    $224.95
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    $224.95
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  • On Sale
    New - H&K G36/SL8 (5.56/.223) Cocking Handle Spring - HKP-01862
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    HK G36, SL8 Spring - Cocking Handle

    H&K Heckler & Koch

    Now: $9.86
    Was: $10.95
    HK German G36 Cocking Handle Spring - All Variants Compatible With: G36 - all variants SL8 - all variants
    Now: $9.86
    Was: $10.95
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    Now: $9.86
    Was: $10.95
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  • On Sale
    New - HK G36 (5.56/.223) Cocking Handle Bushing - HKP-18368 HK G36 Bushing - Cocking Handle -
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    HK G36 Bushing - Cocking Handle -

    Now: $5.36
    Was: $5.95
    G36 Cocking Handle Bushing - US Made
    Now: $5.36
    Was: $5.95
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    Now: $5.36
    Was: $5.95
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  • On Sale
    New - H&K MR556 A4/416 Rear Takedown Pin - HKP-22029 HK416, HK417, MR556, MR762 Takedown Pin - Rear - A4 Style
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    HK416, HK417, MR556, MR762 Takedown Pin - Rear - A4 Style

    H&K Heckler & Koch

    Now: $39.56
    Was: $43.95
    H&K MR556, HK416, HK417, MR762 Rear Takedown Pin Factory A4 rear takedown pin.  Will work for A1 and A4 applications.   Compatible With: HK MR556 A1 and A4 HK416 HK MR762 A1 and A4 HK417 AR-14, M4, M16    
    Now: $39.56
    Was: $43.95
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    Now: $39.56
    Was: $43.95
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  • On Sale
    New - HK 416, MR556 Roll Pin for Charging Handle - HKP - HKP-16536
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    HK416, MR556 Roll Pin - Charging Handle

    Now: $7.16
    Was: $7.95
    HK 416, MR556 Roll Pin for Charging Handle - HKP This is the shorter one that is used on the inside of the charging handle. There are two of these pins used per charging handle.
    Now: $7.16
    Was: $7.95
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    Now: $7.16
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