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 MP5 Receiver Flat - Smooth Top - HKP-21552 HK MP5 Receiver Flat - Smooth Top
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    HK MP5 Receiver Flat - Smooth Top

    HKP HK Parts

    Now: $100.76
    Was: $125.95
    HKP HK MP5 Receiver Flat - Smooth Top The MP5 receiver flat has been meticulously crafted by the original German tool and die maker of the LSC receiver flat, utilizing factory original German prints and specifications. This receiver boasts a flat top,...
    Now: $100.76
    Was: $125.95
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    Was: $125.95
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    New - HKP MP5, MP5K Rear Sight Base - HKP-02450 HK MP5, MP5K Rear Sight Base
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    HK MP5, MP5K Rear Sight Base

    HKP HK Parts

    Now: $15.96
    Was: $19.95
    MP5 & MP5K Rear Sight Base- Weldment The only factory-correct sight base with the factory HK German side axis grooves.  Compatible With: HK MP5, 94 HK MP5K, SP89 HK MP5 40, MP5 10 MAC-5 clones may require custom fitment. Modified components are...
    Now: $15.96
    Was: $19.95
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    New - H&K HK MR762/417 Flush Cup QD End Plate - Black - HKP-21642 HK417, MR762 QD End Plate - Flush Cup
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    HK417, MR762 QD End Plate - Flush Cup

    H&K Heckler & Koch

    Now: $137.66
    Was: $152.95
    H&K HK MR762/417 Flush Cup QD End Plate Factory HK flush end cap with dual QD sockets for ambidextrious sling attachment. Compatible With: HK MR762 HK 417
    Now: $137.66
    Was: $152.95
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    Was: $152.95
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    New - H&K HK G36 Backplate Complete w/ Recoil Assembly - HKP-16735 HK G36 Backplate Complete with Recoil Assembly
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    HK G36 Backplate Complete with Recoil Assembly

    H&K Heckler & Koch

    Now: $179.95
    Was: $199.95
    HK G36 Backplate Complete With Recoil Assembly New HK German G36 Backplate with new G36/SL8 recoil buffer and recoil assembly. This assembly does include the recoil rod retaining screw. This is a great spare or replacement to have on hand. These are also...
    Now: $179.95
    Was: $199.95
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    New - H&K HK MR762/417/G28 Ejection Cover Axle Spring - HKP-16753
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    HK417, MR762, G28 Spring - Ejection Cover Axle

    H&K Heckler & Koch

    Now: $8.96
    Was: $9.95
    H&K HK MR762/417/G28 Ejection Cover Axle Spring New Hk German manufacture for the MR762 & HK 417 firearm. The spring is used on the axle and ejection port cover door to allow it to be closed and spring open. Compatible With: HK MR762 HK 417 HK...
    Now: $8.96
    Was: $9.95
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    New - H&K HK MR556/MR223 Upper Receiver w/ F/A & Ejection Door - HKP-16950 HK MR556, MR223 Upper Receiver w/ F/A & Ejection Door
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    HK MR556, MR223 Upper Receiver w/ F/A & Ejection Door

    H&K Heckler & Koch

    Now: $625.46
    Was: $694.95
    New HK German Partially Pre-Assembled MR556/MR223 Upper Receiver Each unit comes just as shown with the F/A (forward assist) assembly and ejection port door assembly installed from the HK factory.  Compatible With: HK MR556 HK MR223 HK...
    Now: $625.46
    Was: $694.95
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    Now: $625.46
    Was: $694.95
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    New - H&K G36/SL8 (5.56/.223) Cocking Handle - HKP-01853
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    HK G36, SL8 Cocking Handle

    H&K Heckler & Koch

    Now: $50.36
    Was: $55.95
    HK Cocking Handle For G36 & SL8 Bolt Carriers  
    Now: $50.36
    Was: $55.95
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    Was: $55.95
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    New - H&K HK MR556 A4 Ambi Charging Handle - HKP-21933 HK MR556 A4 Charging Handle - Ambi
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    HK MR556 A4 Charging Handle - Ambi

    H&K Heckler & Koch

    Now: $179.95
    Was: $199.95
    H&K HK MR556 A4 Ambi Charging Handle Upgrade your MR556 or HK416-style rifle with this factory H&K ambidextrous charging handle, designed for smooth, reliable operation from either side. Built to Heckler & Koch’s exacting standards,...
    Now: $179.95
    Was: $199.95
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    Was: $199.95
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  • On Sale
    New - H&K HK MR762 Lower Receiver Front Locking Pin - Black - HKP-16602 HK417, MR762 Takedown Pin - Front - A1 Style
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    HK417, MR762 Takedown Pin - Front - A1 Style

    H&K Heckler & Koch

    Now: $53.96
    Was: $59.95
    H&K HK MR762 Lower Receiver Front Takedown Pin - A1 Style This 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 lower receivers and...
    Now: $53.96
    Was: $59.95
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    New - H&K HK MR556/416 Charging Handle Release Latch - HKP-16553 HK416, MR556 Release Latch -  Charging Handle
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    HK416, MR556 Release Latch - Charging Handle

    H&K Heckler & Koch

    Now: $35.96
    Was: $39.95
    H&K HK MR556/416 Charging Handle Release Latch Perfect replacement item for the MR556 & HK 416 charging handle. New HK German manufacture. These can become chewed up and damaged with a hard drop or with heavy use. This is a great item to keep on...
    Now: $35.96
    Was: $39.95
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    Was: $39.95
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  • New - HKP MP5 40/10 Trunnion - HKP-02737 HK MP5 40/10 Trunnion
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    HK MP5 40/10 Trunnion

    HKP HK Parts

    $139.95
    MP5 40 & MP5 10mm Trunnion Machined from ordnance-grade steel and heat-treated to factory specs. Each has the bullet guides pre-installed and included. These are the best USA-made trunnions on the market. Machined to HK spec, making the installation...
    $139.95
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    $139.95
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  • On Sale
    New - HKP HK MP5K/SP89 9mm Flat Receiver - HKP-20733 HK MP5K, SP89 Flat Receiver - 9mm
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    HK MP5K, SP89 Flat Receiver - 9mm

    HKP HK Parts

    Now: $159.96
    Was: $199.95
    MP5K, SP89 Receiver Flat - 9mm New MP5K receiver flat made by the original German tool and die maker of the LSC receiver flat utilizing factory original German prints and specifications. The creator of our receiver flat has been regarded as the premier...
    Now: $159.96
    Was: $199.95
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    Now: $159.96
    Was: $199.95
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