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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    New - H&K HK MR556 M-LOK 16.5" Upper Receiver Assembly - Black - HKP-17366 HK MR556 Upper Receiver Kit -16.5" - M-LOK

    HK MR556 Upper Receiver Kit -16.5" - M-LOK

    H&K Heckler & Koch

    $1,779.95
    New HK Factory German MR556 Upper Kit with M-LOK forearm Includes: Complete MR556 upper receiver with M-LOK forearm MR556 Bolt group Complete Tungsten Filled HK Buffer HK Buffer Spring One 30 Round HK Steel Maritime Magazine No FFL required as the...
    HKP-17366
    $1,779.95
    Out Of Stock
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    $1,779.95
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  • New - HK G36/SL8 (5.56/.223) Cocking Handle Axle Pin - HKP-18367 HK G36, SL8 Cocking Handle Axle Pin - USA
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    HK G36, SL8 Cocking Handle Axle Pin - USA

    USA

    $10.95
    HK G36, SL8 Cocking Handle Axle Pin - US Made This is the rivet pin that is used to attach the swiveling cocking handle to the body of the carrier. These can be replaced as they break and wear. Compatible With: HK G36 models HK SL8 models
    HKP-18367
    $10.95
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  • Out Of Stock
    New - H&K MR556 A4/416 Rear Takedown Pin - HKP-22029 HK416, MR556, HK417, MR762 Takedown Pin - Rear - A4 Style

    HK416, MR556, HK417, MR762 Takedown Pin - Rear - A4 Style

    H&K Heckler & Koch

    $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    
    HKP-22029
    $43.95
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  • New - H&K HK G36/SL8 Complete Recoil Rod Assembly - HKP-01057
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    HK G36, SL8 Recoil Spring Assembly, Complete

    H&K Heckler & Koch

    $69.95
    Recoil Rod Assembly for HK G36 & SL8 New HK factory German G36/SL8 (fits all variants of SL8/G36) recoil rod assembly complete. Great for replacement or for a spare as these have been hard to find.
    HKP-01057
    $69.95
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  • 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

    $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,...
    HKP-21552
    $125.95
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  • HK UMP Magazine Release - Enhanced - Billeted HK UMP Magazine Release - Enhanced - Billeted
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    HK UMP Magazine Release - Enhanced - Billeted

    HKP HK Parts

    $34.95
    HKP HK Parts Enhanced Paddle Magazine Release for HK UMP This is a very common replacement part as they are fairly easy to break on the UMP lower. With this new mag release, you'll get a wider release as well as a much more durable part. Simple &...
    HKP-18758
    $34.95
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  • Out Of Stock
    Used - H&K MP5, MP5K Case Deflector - HKP-00871 HK MP5, MP5K Case Deflector

    HK MP5, MP5K Case Deflector

    H&K Heckler & Koch

    $0.00
    HK German case deflector for receiver flat or receiver for all MP5, HK94, MP5K & SP89 builds. The case deflector is riveted or welded in place on the ejection port of the 9mm receiver/flat to aid in the extraction of the 9mm round. HK MP5, 94 HK...
    HKP-00871
    $0.00
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  • New - HKP MP5 40,10 Magazine Release Paddle Lever - HKP-01274 HK MP5 Magazine Release Paddle Lever - .40 S&W, 10mm
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    HK MP5 Magazine Release Paddle Lever - .40 S&W, 10mm

    HKP HK Parts

    $59.95
    HKP HK Parts Magazine Release Lever for HK MP5 40 and MP5 10mm  
    HKP-01274
    $59.95
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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

    $174.95
    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
    HKP-21642
    $174.95
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  • New - HKP HK MR556/MR762/416/AR-15 Titanium Take Down Pin Set - HKP-17936
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    HK416, MR556, MR762, AR-15 Take Down Pin Set - Titanium

    HKP HK Parts

    $29.95
    AR15, M4, MR556, MR762, AR10 Enhanced Take Down Pin Set Front & Rear - Titanium Custom ultra strong pure titanium front and rear take down pin set. Each set included both the front and rear pins for any AR mil-spec style lower. Compatible...
    HKP-17936
    $29.95
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  • Out Of Stock
    New - H&K HK G28 Buffer Tube - Black - HKP-16741 HK G28 Buffer Tube

    HK G28 Buffer Tube

    H&K Heckler & Koch

    $199.95
    HK G28 Buffer Tube / Receiver Extension 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. Made in Germany by HK.
    HKP-16741
    $199.95
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  • Out Of Stock
    New - HKP 416 10.4" 5.56 Complete Upper Receiver Assembly - HKP-17662 HK416 Upper Receiver Kit - 10.4" - 5.56

    HK416 Upper Receiver Kit - 10.4" - 5.56

    HKP HK Parts

    $2,485.95
    HKP 416 10.4" 5.56 Complete Upper Kit Complete Each kit includes the complete upper assembly, bolt group, tungsten buffer, & high-reliability SS recoil spring. This upper kit is a complete gas piston HK 416 style upper assembly that will drop on your...
    HKP-17662
    $2,485.95
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    $2,485.95
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