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 Rear Stock Pin Bushing Weldment - HKP-17573
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    HK Stock Pin Bushing Weldment

    HKP HK Parts

    Now: $3.16
    Was: $3.95
    HK Stock Push Pin Bushing Weldment All-steel stock pin bushing weldment for welding in the rear of the flat. This bushing welds into the folded flat and guides the large push pin through the receiver to hold the stock to the receiver. Compatible...
    Now: $3.16
    Was: $3.95
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    Was: $3.95
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  • On Sale
    New - PTR HK 91/G3 (7.62x51/.308) Receiver Flat - HKP-02320 HK91, G3 Receiver Flat - US Made
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    HK91, G3 Receiver Flat - US Made

    PTR

    Now: $89.95
    Was: $99.95
    HK G3, 91, PTR & CETME Flat - PTR Made by PTR with original HK tooling using factory specifications and a properly stamped receiver. No FFL is required as this is an unfolded flat that ships directly to the customer. This US made receiver flat...
    Now: $89.95
    Was: $99.95
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    Was: $99.95
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    New - PTR HK 91/G3/51 (7.62x51/.308) Flat With Weldment Set - HKP-02086 HK91, G3, CETME Receiver Flat with Weldment Set
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    HK91, G3, CETME Receiver Flat with Weldment Set

    PTR

    Now: $150.25
    Was: $166.95
    HK91, G3, PTR, CETME Flat & Weldment Combo - PTR Made by PTR91 on original HK tooling using factory specifications and a properly stamped receiver ready to roll and build. No FFL transfer is required as this is an un-folded flat.  Compatible...
    Now: $150.25
    Was: $166.95
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    Now: $150.25
    Was: $166.95
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    New - HKP MP5, HK94 Case Deflector Rivet - HKP-18008
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    HK MP5, HK94 Case Deflector Rivet - US

    HKP HK Parts

    Now: $1.56
    Was: $1.95
    HKP MP5, HK94 Case Deflector Rivet Each case deflector will require 2 rivets to attach the case deflector to the receiver or flat. If you want the factory look and feel of doing it right these rivets are a must. These are a factory correct rivet that...
    Now: $1.56
    Was: $1.95
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  • On Sale
    New - HKP Semi Shelf Weldment - Metal Grip Housing - HKP-16657 HK Semi Shelf Weldment - Metal Grip Housing
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    HK Semi Shelf Weldment - Metal Grip Housing

    HKP HK Parts

    Now: $11.96
    Was: $14.95
    HKP Semi Shelf Weldment Metal Grip Housing For Semi-Auto Trigger Packs This HK German specification metal trigger frame weldment is designed for converting SEF style housings from full auto to semi-auto. This weldable block or shelf is essential for...
    Now: $11.96
    Was: $14.95
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    New - Semi Auto Shelf For Receiver - Billeted - HKP-01521
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    Semi Auto Shelf For Receiver - Billeted

    Now: $17.95
    Was: $19.95
    Semi Auto Shelf For Receiver - Billeted HK Semi Auto Shelf milled from one solid billet to HK's factory specifications (no castings here). This is the needed receiver shelf that is welded to the receiver to allow the use of the clipped & pinned...
    Now: $17.95
    Was: $19.95
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    Now: $17.95
    Was: $19.95
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  • On Sale
    New - HKP Picatinny Rail For HK Receivers - 17 Slot - HKP-01446 HK Picatinny Rail For HK Receivers - 17 Slot
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    HK Picatinny Rail For HK Receivers - 17 Slot

    HKP HK Parts

    Now: $55.96
    Was: $69.95
    HKP Picatinny Rail For HK Receivers - 17 Slot Mil-Spec all steel Picatinny rail in the white. Relief cut for HK receivers and made for mounting scopes and optics to HK builds. This unit easily welds to the top of your HK receiver. Compatible With: HK...
    Now: $55.96
    Was: $69.95
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    Was: $69.95
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  • On Sale
    New - HKP HK21 T-Rail Set - 7.62x51/.308 - HKP-21457 HK21, FMP21 T-Rail Set
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    HK21, FMP21 T-Rail Set

    HKP HK Parts

    Now: $95.96
    Was: $119.95
    HKP HK 21 (7.62x51/.308) Factory Style T-Rail Set HKP HK21 US made rails for all HK21 and FMP21 builds. Our steel T-rails incorporate an updated radius to address a weak link in previous iterations.  Compatible With:  HK21 FMP21
    Now: $95.96
    Was: $119.95
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    Was: $119.95
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    New - HKP Semi Auto Shelf for Receiver - Billeted - HKP-21470 HK Semi Auto Shelf for Receiver - Billeted
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    HK Semi Auto Shelf for Receiver - Billeted

    HKP HK Parts

    Now: $14.36
    Was: $17.95
    HKP Semi Auto Shelf for Receiver - Billeted HK Semi Auto Shelf, Hanger Block to HK's factory specifications for c/p trigger housings. Weld on shelf that is the needed receiver block that welds to the rearward portion of the magwell to allow the use of...
    Now: $14.36
    Was: $17.95
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    Was: $17.95
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  • On Sale
    New - HKP Flat Bending Billeted Jig Set For All HK Style Flats - HKP-19583 HK Receiver Flat Bending Jig Set - Billet Aluminum
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    HK Receiver Flat Bending Jig Set - Billet Aluminum

    HKP HK Parts

    Now: $314.97
    Was: $449.95
    Flat Bending Jig Set For All HK Style Flats - Billeted - Aluminum Aluminum billeted universal flat bending jig for all HK receiver flats including PTR .308 flats and the PTR/LSC flats. Each bending jig comes complete with all the pieces you need for...
    Now: $314.97
    Was: $449.95
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    Was: $449.95
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  • New - HKP HK Mil-Spec AR Brace/Stock Adapter & Buffer Tube - HKP-16583 HK91, G3, HK93 Stock or Brace Adapter - with Mil-Spec AR Buffer Tube
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    HK91, G3, HK93 Stock or Brace Adapter - with Mil-Spec AR Buffer Tube

    HKP HK Parts

    $124.95
    HKP HK Mil-Spec AR Brace/Stock Adapter & Buffer Tube AR15 to HK 90 series stock adapter for AR15 stocks that includes the mil-spec buffer tube and castle nut to use any mil-spec AR15/M16 stock of your choice on your HK rifle or SBR build. With the...
    $124.95
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    $124.95
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  • On Sale
    New - LSC MP5 9mm Receiver Flat - HKP-20555 LSC MP5 9mm Receiver Flat
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    LSC MP5 9mm Receiver Flat

    LSC

    Now: $179.95
    Was: $199.95
    MP5 Receiver Flat - LSC LSC HK MP5 receiver flat is the most in spec flat that has ever been available. The best option for your HK German parts kit build. This flat is considered by many to be most sought after HK flat available on the market and...
    Now: $179.95
    Was: $199.95
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    Now: $179.95
    Was: $199.95
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