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 - H&K HK MR556/416 E1 Incomplete Charging Handle - Black - HKP-17540 HK416 E1, MR556 Charging Handle - Incomplete
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    HK416 E1, MR556 Charging Handle - Incomplete

    H&K Heckler & Koch

    Now: $98.95
    Was: $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 HK 416 HK M27
    Now: $98.95
    Was: $109.95
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    Was: $109.95
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  • On Sale
    HK MP5 Case Deflector - 9mm, .40 S&W Receivers HK MP5 Case Deflector - 9mm, .40 S&W Receivers
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    HK MP5 Case Deflector - 9mm, .40 S&W Receivers

    HKP HK Parts

    Now: $19.96
    Was: $24.95
    HKP HK MP5 Case Deflector - 9mm, .40 Receivers US-made steel case deflector for HK MP5 and MP5K receivers in 9mm and .40 S&W. Installs on the ejection-port flat, rivet or weld, to redirect brass and support reliable extraction on MP5 and MP5K style...
    Now: $19.96
    Was: $24.95
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  • On Sale
    New - H&K HK MR762/417 Upper Receiver - Incomplete - HKP-16624 HK417, MR762 Upper Receiver - Incomplete
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    HK417, MR762 Upper Receiver - Incomplete

    H&K Heckler & Koch

    Now: $718.16
    Was: $797.95
    H&K HK MR762/417 Upper Receiver - Incomplete Stripped upper receiver with threaded piston guide bushing installed. Compatible With: HK MR762 HK417
    Now: $718.16
    Was: $797.95
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    Was: $797.95
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  • Out Of Stock
    On Sale
    New - HKP HK MR556/416 Upper 8" 416C Style Conversion Kit - HKP-18629 HK416, MR556 Upper 8" 416C Style Conversion Kit

    HK416, MR556 Upper 8" 416C Style Conversion Kit

    HKP HK Parts

    Now: $1,028.76
    Was: $1,285.95
    Upper Conversion Kit for HK416 and MR556 8 inch barrel - HK 416C Style Finally an answer for all of those that have been wanting as close to the original, rare unicorn of a find HK 416C 8" barrel conversion kit for 416 or MR556. Each conversion kit...
    Now: $1,028.76
    Was: $1,285.95
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  • Out Of Stock
    On Sale
    HK416, MR556 Castle Nut - USED H&K Heckler & Koch HKP-15230-USED HK416, MR556 Castle Nut - USED H&K Heckler & Koch HKP-15230-USED

    HK416, MR556 Castle Nut - USED

    H&K Heckler & Koch

    Now: $19.95
    Was: $32.95
     HK416, MR556 Castle Nut - USED SOLD INDIVIDUALLY USED PARTS ARE SOLD AS IS. THIS PART IS NOT ELIGIBLE FOR RETURN. ALL BLEMISHED PART SALES ARE FINAL. New HK German manufacture. This buffer tube castle nut will fit both mil-spec and commercial...
    Now: $19.95
    Was: $32.95
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  • On Sale
    HK G3 - FMP Early Type Demilled Front End - No Cocking Handle Assembly FMP HK CONTRACT HKP-22377 HK G3 - FMP Early Type Demilled Front End - No Cocking Handle Assembly FMP HK CONTRACT HKP-22377
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    HK FMP G3 Early Type De-Milled Front End - No Cocking Handle Assembly

    FMP HK CONTRACT

    Now: $62.06
    Was: $68.95
    HK G3 - FMP Early Type De-milled Front End - No Cocking Handle Assembly Early style G3 front end with no hanger from de-milled FMP G3 parts kits. Perfect for custom builds.  Includes: Cocking tube Trunnion Barrel pin
    Now: $62.06
    Was: $68.95
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    Was: $68.95
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  • On Sale
    New - H&K MR762 A4 Buffer Tube - HKP-21964 HK MR762 A4 Buffer Tube
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    HK MR762 A4 Buffer Tube

    H&K Heckler & Koch

    Now: $86.36
    Was: $95.95
    H&K MR762 A4 Buffer Tube Factory German-made buffer tube for the MR762 A4. Compatible With: HK MR762 A1/A4
    Now: $86.36
    Was: $95.95
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    Was: $95.95
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  • On Sale
    New - H&K HK MR556 A4 Complete Upper w F/A & Ejection Door - HKP-21929 HK MR556 A4 Complete Upper - F/A & Ejection Door
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    HK MR556 A4 Complete Upper - F/A & Ejection Door

    H&K Heckler & Koch

    Now: $761.36
    Was: $845.95
    H&K HK MR556 A4 Complete Upper w F/A Ejection Door The H&K MR556 A4 Complete Upper is a superior factory assembly that comes fully equipped with a forward assist and an ejection port door, providing unparalleled reliability and precision. This...
    Now: $761.36
    Was: $845.95
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    Was: $845.95
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  • On Sale
    New - H&K 417/MR762/G28 Complete Buffer Tube - HKP-21872 HK416, MR556 Complete Buffer Tube
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    HK416, MR556 Complete Buffer Tube

    H&K Heckler & Koch

    Now: $159.25
    Was: $176.95
    H&K HK416, MR556 Complete Receiver Extension/Buffer Tube Genuine German complete receiver extension for the 416 based 5.56 / .223 platforms. Compatible With: HK416 MR556
    Now: $159.25
    Was: $176.95
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    Now: $159.25
    Was: $176.95
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  • Used - H&K HK UMP Demilled Extended Rear Receiver Section - HKP-19798 HK UMP Demilled Extended Rear Receiver Section
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    HK UMP Demilled Extended Rear Receiver Section

    H&K Heckler & Koch

    $999.95
    HK German Factory UMP  Receiver Section - Extended Demilled factory HK UMP rear receiver section perfect for a USC-UMP conversion. With the folding stock attachment point intact right in front of the ejection port, this extended receiver section is...
    $999.95
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    $999.95
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  • On Sale
    New - H&K HK MR762/417 Plate For Charging Handle - HKP-16843 HK417, MR762 Charging Handle Plate
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    HK417, MR762 Charging Handle Plate

    H&K Heckler & Koch

    Now: $17.95
    Was: $19.95
    HK MR762, HK417 Plate For Charging Handle Compatible With: HK MR762 HK417
    Now: $17.95
    Was: $19.95
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  • On Sale
    HK G3 Complete Parkerized Rear Receiver Section - SURPLUS FMP HK CONTRACT HKP-22375 HK G3 Complete Parkerized Rear Receiver Section - SURPLUS FMP HK CONTRACT HKP-22375
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    HK FMP G3 Rear Receiver Section - SURPLUS

    FMP HK CONTRACT

    Now: $22.45
    Was: $24.95
    H&K G3 Complete Parkerized Rear Receiver Section without Rear Sight - SURPLUS UNIT CONDITION WILL VARY  Steel rear receiver section manufactured by FMP on HK tooling. Does not include the rear sight.  Compatible with: HK G3, HK91 In-spec...
    Now: $22.45
    Was: $24.95
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    Now: $22.45
    Was: $24.95
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