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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  • Out Of Stock
    Used - H&K 93/53/33 (5.56/.223) Rear Receiver Section - HKP-16481 HK33, HK53, HK93 Rear Receiver Section
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    HK33, HK53, HK93 Rear Receiver Section

    H&K Heckler & Koch

    $79.95
    H&K 93/53/33 (5.56/.223) Rear Receiver Section Each rear receiver section is from a factory German HK 33/53 that was demilled and includes the welded on rear sight base and push pin bushing intact.
    HKP-16481
    $79.95
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  • On Sale
    HK German Bayonet Adapter Without Hardware - Incomplete - USED HK German Bayonet Adapter Without Hardware - Incomplete - USED
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    HK German Bayonet Adapter Without Hardware - Incomplete - USED

    H&K Heckler & Koch

    Now: $74.96
    Was: $159.95
    HK German Bayonet Adapter Without Hardware - Incomplete - USED   SOLD INDIVIDUALLY - VARYING CONDITION SHOWN   INCOMPLETE USED PARTS ARE SOLD AS IS. THIS PART IS NOT ELIGIBLE FOR RETURN. ALL USED PART SALES ARE FINAL. HK German Bayonet...
    HKP-00021-B
    Now: $74.96
    Was: $159.95
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    Was: $159.95
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  • On Sale
    HK417, MR762 Upper Receiver and Handguard - Flecktarn HK417, MR762 Upper Receiver and Handguard - Flecktarn
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    HK417, MR762 Upper Receiver and Handguard - Flecktarn

    H&K Heckler & Koch

    Now: $1,340.95
    Was: $1,489.95
    HK417, MR762 Upper Receiver and 13.5" Handguard - Flecktarn Factory HK MR762 matching flecktarn upper receiver and 13.5" handguard.   ONLY 3 SETS AVAILABLE AND WILL NOT BE RESTOCKED Compatible With: HK MR762 HK417  
    HKP-99325
    Now: $1,340.95
    Was: $1,489.95
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    Was: $1,489.95
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  • On Sale
    Used - H&K MP5 40/10 Factory Trunnion - USED - HKP-99173 HK MP5 Trunnion - .40 S&W, 10mm - Factory - USED
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    HK MP5 Trunnion - .40 S&W, 10mm - Factory - USED

    H&K Heckler & Koch

    Now: $223.46
    Was: $549.95
    H&K MP5 40/10 Factory Trunnion - USED ONLY 1 UNIT AVAILABLE - AS PICTURED Used genuine German trunnion with round guides. Compatible With: HK MP5 40/10 THIS CLOSEOUT PART IS NOT ELIGIBLE FOR RETURN, REFUND, OR EXCHANGE.  SALE IS FINAL.
    HKP-99173
    Now: $223.46
    Was: $549.95
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    Was: $549.95
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  • Out Of Stock
    New - HK UMP Paddle Mag Release Complete Assembly - HKP-19499 HK UMP Paddle Magazine Release Assembly, Complete
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    HK UMP Paddle Magazine Release Assembly, Complete

    USA

    $19.95
    UMP Paddle Magazine Release - US Made - Assembly Complete New UMP Mag release. This is a very common repair and replacement part as they are fairly easy to break on the UMP lower. Simple and easy to install no gunsmith needed or required. Compatible...
    HKP-19499
    $19.95
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  • Out Of Stock
    New - H&K MR556 & HK416 (5.56x45/.223) Upper Conversion Kit - Threaded 1/2x28 - HKP-17877 HK416, MR556 Upper Conversion Kit - Threaded 1/2x28, - 5.56x45 / .223
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    HK416, MR556 Upper Conversion Kit - Threaded 1/2x28, - 5.56x45 / .223

    HKP HK Parts

    $699.95
    H&K MR556 & HK416 (5.56x45/.223) Upper Conversion Kit - Threaded 1/2x28 Finally an answer for all of those that have been wanting a 14.5" upper for an HK416 or MR556. This conversion kit adds an upper or a barrel option for your MR556, CR556...
    HKP-17877
    $699.95
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    $699.95
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  • Out Of Stock
    New - HKP HK USC (.45 ACP) Carbine Mag Release - Extended - HKP-17918
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    HK USC Magazine Release - Extended

    HKP HK Parts

    $24.95
    HKP HK Parts Alloy Extended Magazine Release for HK USC Billeted alloy USC magazine release. This is a very common repair and replacement part as they are fairly easy to break on the USC lower. With this new metal mag release you get more surface area...
    HKP-17918
    $24.95
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    $24.95
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  • Out Of Stock
    Used - H&K UMP (.40 S&W/.45 ACP/9mm) Demilled Rear Receiver Section - HKP-01659 HK UMP Rear Receiver Section - Demilled
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    HK UMP Rear Receiver Section - Demilled

    H&K Heckler & Koch

    $0.00
    HK UMP Demilled Receiver Section This is a demilled factory HK UMP rear receiver section that is perfect for the new Tom Bostic USC-UMP conversions. This section is the perfect length in order to do the USC, UMP conversion. Last one available.
    HKP-01659
    $0.00
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  • Out Of Stock
    New - HK UMP .40 S&W, .45 ACP, 9 mm Paddle Mag Release - HKP-18773
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    HK UMP Paddle Magazine Release

    USA

    $9.95
    US Made Paddle Magazine Release for HK UMP New UMP Mag release. This is a very common repair and replacement part as they are fairly easy to break on the UMP lower. Simple and easy to install no gunsmith needed or required. Compatible With: UMP Please...
    HKP-18773
    $9.95
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    $9.95
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  • Out Of Stock
    New - MM HK 21 (7.62x51/.308) Trunnion - HKP-00246 HK21 Trunnion
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    HK21 Trunnion

    H&K Heckler & Koch

    $0.00
    US Made HK21 Trunnion By Michael's Machine (MM) These are the finest US-made trunnions available.
    HKP-00246
    $0.00
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  • Out Of Stock
    New - MM HK 23E (5.56/.223) Complete Feed Mechanism - HKP-17578
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    HK23E Feed Mechanism - Complete - 5.56 / .223

    Michaels Machines

    $3,999.95
    MM HK 23E (5.56/.223) Complete Feed Mechanism New US manufactured HK23E feed mechanism complete with top plate and push pin. The complete unit a great spare to have on hand.  Compatible With: Factory HK23E and MM23E firearms
    HKP-17578
    $3,999.95
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    $3,999.95
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  • Out Of Stock
    Used - H&K 93/33/53 Paddle Magazine Release Set Complete-Used - HKP-00707
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    HK33, HK53, HK93 Paddle Magazine Release Set Complete - Used

    H&K Heckler & Koch

    $0.00
    HK 93, HK33, & HK 53 Paddle magazine release set complete all pieces-Used
    HKP-00707
    $0.00
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    $0.00
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