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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HKP MP5 40/10 Trunnion
HKP HK Parts
$139.95MP5 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...HKP-02737$139.95 -
HKP MP5, MP5K Rear Sight Base
HKP HK Parts
$19.95MP5 & 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 Clone or other custom buildsHKP-02450$19.95 -
H&K HK MR762/417/G28 Receiver End Plate
H&K Heckler & Koch
$24.95HK MR762, G28 & HK 417 End Plate or locking plate for Receiver New HK German factory. Compatible With: HK MR762 HK 417 HK G28HKP-16610$24.95 -
H&K MP5 Rear Receiver Section
H&K Heckler & Koch
$14.95H&K MP5 Rear Receiver Section HK German demilled receiver section with rear sight base as installed at the factory. MP5 & HK94 Factory HK rear sight bases (portion welded to MP5 receiver), you get the actual demilled section of an MP5 receiver...HKP-02167$14.95 -
HKP HK 416 11.5" 5.56 Complete Upper Receiver Assembly
HKP HK Parts
$2,485.95HKP HK 416 11.5" 5.56 Complete Upper Kit Complete HKP 416 style complete upper assembly. This top-tier assembly seamlessly fits onto your mil-spec lower or a STS 416 lower, providing the perfect solution for those seeking an 11.5" 416 style upper without...HKP-21539$2,485.95 -
HKP HK MP5K/SP89 9mm Flat Receiver
HKP HK Parts
$199.95MP5K, 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...HKP-20733$199.95 -
RCM HK PSG1 Style Trunnion
RCM
$119.95HK PSG1 Trunnion- PTR- USA RCM trunnion for custom PSG1, MSG90, & other custom HK91/G3 type builds. Machined completely from ordnance grade 9310 enhanced steel and heat treated to exact HK specifications. This item is the best USA made trunnion on...HKP-20522$119.95 -
H&K HK 416A5 Stripped Upper Receiver - Black
H&K Heckler & Koch
$599.95HK 416A5 - Stripped Upper Receiver - Black This is the factory correct receiver for a true 416 build as it features the M16 relief cut in the bottom, rear portion of the receiver (shown in last pricture). Compatible With: HK 416 HK MR223 HK MR556 Need...HKP-18786$599.95 -
HKP Mil-Spec Buffer Tube Kit
HKP HK Parts
$42.95Mil-Spec Buffer Tube Kit Compatible With: HK MR556 & 416 AR-15 style platforms Includes: Made with T7 7075 aircraft-grade aluminum Made in the USA with a polished inside tube Mil-Spec triple hard coat Teflon anodized finish Each unit comes with a...HKP-02735$42.95 -
Out Of Stock
H&K 416A5 RAL 8K Stripped Upper Receiver
H&K Heckler & Koch
$0.00HK German Un-Assembled Stripped HK 416A5 Upper Receiver - RAL 8K Brand new factory German RAL 8000 416A5 upper receiver. Compatible With: HK MR556 HK MR223 HK 416 Looking for a matching lower for your build? STS416 A5 LOWER - Specialized Tactical...HKP-18787$0.00 -
Out Of Stock
HKP HK 416 Upper Receiver
HKP HK Parts
$489.95US Made Complete HK 416, MR556 Style Upper Receiver New US made HK416/MR556 style upper receiver. Includes: Upper receiver Forward assist assembly Ejection port door assembly Piston guide Compatible With: HK MR556 HK MR223 HK 416 Need a...HKP-17783$489.95 -
Out Of Stock
H&K HK G36 Complete 3X Single Optic Carrying Handle
H&K Heckler & Koch
$695.99H&K HK G36 Complete 3X Single Optic Carrying Handle Brand new. Mounting hardware offered separately.HKP-16388$695.99 -
HKP HK MP5 Receiver Flat - Smooth Top
HKP HK Parts
$125.95HKP 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 -
HKP MP5K 40/10 Receiver Flat
HKP HK Parts
$199.95MP5K-40, MP5K-10 Receiver Flat - USA Receiver Flat for use with a MP5K-40 or MP5K-10mm build. Please note: This is for the flat as picture no weldments are included. ***This US made receiver flat counts as one required 922r compliant part***HKP-18033$199.95 -
Out Of Stock
H&K MP5K/SP89/SP5K 9mm Incomplete End Cap
H&K Heckler & Koch
$0.00HK Factory German MP5K, SP-89, SP5K End Cap - Incomplete Each pistol end cap is OEM HK German MP5K, MP5K-N, SP5K, SP89 stripped end cap. Compatible With: MP5K SP89 SP5K MP5K-N MP5K-PDW MP5K clones or other custom buildsHKP-18208$0.00 -
B&T MP5, 94 Low Mount, Extra Long Scope Rail
B&T Brugger & Thomet
$239.95B&T MP5, 94 Low Mount, Extra Long Scope Rail Swiss made, military grade, B&T MP5 extra long low-profile scope mount. Requires the removal of the MP5 rear sight. Provides the longest possible Picatinny rail. Specifications: Color: Black Height...HKP-16881$239.95 -
H&K HK SL8, HK G36 Top Rail Screw
H&K Heckler & Koch
$14.95HK SL8 & G36 Top Rail Screw This rail screw is the standard length rail screw used for all SL8 and G36 top rails. With the exception of the dual and single option models. A must have part and an easy part to loose or strip. Grab yours to have...HKP-16390$14.95 -
HKP V51 Backplate
HKP HK Parts
$167.95HKP V51 Backplate HK Parts brings you a long lost part that was no longer available till now. The Vector Arms V51 firearms was one of the most aclaimed PDW of its time but replacement parts have become difficult to source. We now take like new G3...HKP-21201$167.95 -
Out Of Stock
MM HK PSG1/MSG90/91/G3 (7.62x51/.308) T-Rail Reinforcement Set For Receiver
Michaels Machines
$299.95HK Receiver Reinforcement T-Rail Set For Left and Right Sides T-rails are used to strengthen HK receivers or for custom builds. These are the finest T-rails available on the market. Made from enhanced steel and perfect for that custom HK project...HKP-00236$299.95 -
HK 417 German Parts Kit w/ 12" Barrel
H&K Heckler & Koch
$26,000.00HK German 417 Assaulter 12" Parts Kit - Unfired The ultimate HK unicorn. Have you ever seen one let along seen a brand new German UNFIRED HK417 Assaulter parts kit with EVERY single part with the exception of the stripped lower? This is the ultimate HK...HKP-18433$26,000.00 -
B&T HK G36/SL8 (5.56/.223) Mounting Rail
B&T Brugger & Thomet
$149.95B&T HK G36/SL8 (5.56/.223) Mounting Rail B&T Mounting Rail NAR for HK G36, SL8 HK carrying handle, Spanish Military Version. B&T Switzerland is an HK OEM manufacturer and produces top quality accessories for military and law enforcement...HKP-16867$149.95 -
B&T HK MSG90 (7.62x51/.308) Extended Swiss Mount
B&T Brugger & Thomet
$299.95Extended B&T Mounting Rail for HK MSG90 with Support for Brass Catcher This is the finest MSG90 scope/brass catcher mount available! Specifications: Color: Black Height max: 22.5 mm Length max: 340 mm Length of top rail: 332.5 mm Material: Aluminum...HKP-17285$299.95 -
H&K HK MR762 Upper Receiver - Incomplete
H&K Heckler & Koch
$889.95HK MR762, HK 417 Incomplete Upper Receiver This stripped upper receiver includes the insalled threaded piston guide bushing.HKP-16624$889.95 -
H&L HK G36, HK SL8 Roll Pin for Gas Piston - Black
H&K Heckler & Koch
$9.95H&L HK G36, HK SL8 Roll Pin for Gas Piston - BlackHKP-16386$9.95 -
HKP HK 416, MR556 Upper Receiver Forging
HKP HK Parts
$88.95HKP HK 416 A1/A3, MR556 Upper Receiver Forging HK Parts' very own 416 upper receiver forging. This is the first time that these forgings have been made available to the public. Our receivers come with the ever popular Cerro Forge "keyhole" marking. Cerro...HKP-21008$88.95 -
HKP QD End Cap with Buffer - SP5
HKP HK Parts
$99.95HK SP5 - Quick Detach End Cap With this SP5 QD end cap upgrade you will get a heavier buffer to internally protect your firearm and keep your bolt carrier in tip top condition for years to come. Machined aircraft grade aluminum and Cerakoted for the best...HKP-20757$99.95 -
HK G3 - FMP Early Type Demilled Front End
EBO
$99.95HK G3 - FMP Early Type Demilled Front End Early style G3 front end with no hanger. These are the perfect option for those doing custom builds. Good condition over all. Includes: Cocking tube Complete cocking handle assembly Trunnion Barrel pinHKP-20845$99.95 -
H&K 93/53/33 (5.56/.223) Rear Receiver Section
H&K Heckler & Koch
$79.95H&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 -
Out Of Stock
H&K HK MR556/MR223 A5 Incomplete Upper Receiver - Black
H&K Heckler & Koch
$0.00HK German Un-Assembled/Stripped HK MR556/MR223 A5 Upper Receiver Factory HK MR556 A5 upper receiver. This is the semi-auto MR556 variant. Compatible With: HK MR556 HK MR223 HK 416*** Need a matching lower for your build? STS416 A5 LOWER -...HKP-18785$0.00 -
Out Of Stock
H&K HK UMP Demilled Extended Rear Receiver Section
H&K Heckler & Koch
$0.00HK German Factory UMPÂ Receiver Section - ExtendedThis 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. Just in only...HKP-19798$0.00 -
Out Of Stock
H&K HK416, MR556 Ejection Port Cover - FDE
H&K Heckler & Koch
$0.00HK German HK 416, MR556 Ejection Port Cover In RAL7008 -FDE HK manufactured newer polymer style cover assembly found on the latest HK 416 & MR556's. This item can also be used on other AR15 style projects to enhance the project with the finest...HKP-19450$0.00 -
Out Of Stock
H&K UMP (.40 S&W/.45 ACP/9mm) Demilled Rear Receiver Section
H&K Heckler & Koch
$0.00HK 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 -
Out Of Stock
H&K UMP (.40 S&W/.45 ACP/9mm) Incomplete Pistol Grip (0,1)
H&K Heckler & Koch
$0.00UMP Pistol Grip Stripped & Incomplete - 2 Position (0,1) Pictogram New HK German manufacture, rare and hard to find. If you have an HK USC you can use this housing with the USC lower internals for a complete USC to UMP lower assembly that you can use...HKP-17815$0.00 -
Out Of Stock
HKP Magazine Catch - Latest Style
HKP HK Parts
$19.95HKP Magazine Catch - Latest Style New, latest generation 1-piece 9mm mag catch. If you have issues with mags locking in place on clones or non-HK German firearms, it may be that you need this upgrade. One-piece constructiong versus the older generation...HKP-17571$19.95 -
Out Of Stock
MM HK 21 (7.62x51/.308) Trunnion
H&K Heckler & Koch
$0.00US Made HK21 Trunnion By Michael's Machine (MM) These are the finest US-made trunnions available.HKP-00246$0.00 -
HKP HK MP5K Receiver Flat - Smooth Top
HKP HK Parts
$129.95HKP HK MP5K Receiver Flat - Smooth Top The MP5K 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-21550$129.95