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 MR556 A4 16.5″ 5.56 M-LOK Upper Receiver Kit - HKP-21909 MR556 A4 Upper Receiver Kit - 16.5″ - 5.56 - M-LOK

    MR556 A4 Upper Receiver Kit - 16.5″ - 5.56 - M-LOK

    H&K Heckler & Koch

    Now: $1,616.36
    Was: $1,939.00
    H&K MR556 A4 16.5″ 5.56 M-LOK Upper Receiver Kit This kit includes a complete upper receiver/barrel assembly, allowing Mil-Spec 5.56mm AR-style rifles to be retrofitted to HK’s piston and pusher rod system. This system utilizes a piston...
    Now: $1,616.36
    Was: $1,939.00
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    Now: $1,616.36
    Was: $1,939.00
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    New - H&K HK MR556 M-LOK 16.5" Upper Receiver Assembly - Black - HKP-17366 MR556 Upper Receiver Kit -16.5" - M-LOK

    MR556 Upper Receiver Kit -16.5" - M-LOK

    H&K Heckler & Koch

    Now: $1,601.96
    Was: $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...
    Now: $1,601.96
    Was: $1,779.95
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    Now: $1,601.96
    Was: $1,779.95
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    New - H&K MR556 A4 11″ 5.56 M-LOK Upper Receiver Kit - HKP-21910 HK MR556 A4 Upper Receiver Kit - 11"- M-LOK

    HK MR556 A4 Upper Receiver Kit - 11"- M-LOK

    H&K Heckler & Koch

    Now: $1,799.06
    Was: $1,998.95
    H&K Heckler & Koch MR556 Upper Receiver Kit A4 -11″ - M-LOK  This kit includes a complete upper receiver/barrel assembly, allowing Mil-Spec 5.56mm AR-style rifles to be retrofitted to HK’s piston and pusher rod system. This...
    Now: $1,799.06
    Was: $1,998.95
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    Now: $1,799.06
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    New - HKP HK 416 11.5" 5.56 Complete Upper Receiver Assembly - HKP-21539 HK416 Upper Receiver Kit - 11.5" - 5.56

    HK416 Upper Receiver Kit - 11.5" - 5.56

    HKP HK Parts

    Now: $1,988.76
    Was: $2,485.95
    HKP HK 416 11.5" 5.56 Complete Upper Kit Complete This top-tier assembly seamlessly fits onto your mil-spec lower or an STS 416 lower, providing the perfect solution for those seeking an 11.5" 416 style upper without breaking the bank. Each unit is...
    Now: $1,988.76
    Was: $2,485.95
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    Now: $1,988.76
    Was: $2,485.95
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  • Out Of Stock
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    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

    Now: $1,988.76
    Was: $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...
    Now: $1,988.76
    Was: $2,485.95
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    Now: $1,988.76
    Was: $2,485.95
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    New - H&K 416A5 RAL 8K Stripped Upper Receiver - HKP-18787 HK416 A5 Stripped Upper Receiver - RAL8000
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    HK416 A5 Stripped Upper Receiver - RAL8000

    H&K Heckler & Koch

    Now: $1,403.96
    Was: $1,559.95
    HK German Un-Assembled - Stripped HK416 A5 Upper Receiver - RAL 8K Brand new factory German RAL 8000 HK416A5 upper receiver. Compatible With: HK416 HK MR556 HK MR223 Looking for a matching lower for your build?  STS416 A5 LOWER - Specialized...
    Now: $1,403.96
    Was: $1,559.95
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