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 Replacement Buffer for Folding Stock or End Cap
HKP HK Parts
$3.49HKP MP5 Replacement Buffer for Folding Stock or End Cap Spare replacement buffer for choate folding stocks or end caps. Compatible With: Choate MP5 and MP5K Stocks or End Caps (NOT compatible with MP5 .22 LR)HKP-18735$3.49 -
HKP Rear Stock Pin Bushing Weldment
HKP HK Parts
$3.95HK Rear Stock Push Pin Bushing Weldment All-steel rear 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...HKP-17573$3.95 -
DTAC Mag Paddle Bushing With Pin For Semi Builds
DTAC Dakota Tactical
$9.89DTAC Mag Paddle Bushing With Pin For Semi-Builds This part is made 100% in the US from 17-4 stainless steel. Latest production with patent pending anti-binding enhancement upgrade. Accurate tolerance for easy movement with minimal play. It has an...HKP-02194$9.89 -
Choate MP5 & HK94 End Cap & Sling Swivel
Choate
$36.95Choate MP5 & HK94 End Cap and Sling Swivel Made in the USA, MP5 and HK94 end cap features an extra thick heavy-duty rubber buffer that is replaceable with a simple screwdriver. Each HK end cap also features a sling swivel for use with all types of...HKP-00115$36.95 -
PTR HK 91/G3/51 (7.62x51/.308) Flat With Weldment Set
PTR
$166.95HK91, 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 is required as this is an unfolded flat. Compatible With: HK G3...HKP-02086$166.95 -
Semi Auto Shelf For Receiver - Billeted
$19.95Semi 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...HKP-01521$19.95 -
HKP Semi Shelf Weldment - Metal Grip Housing
HKP HK Parts
$14.95HKP 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...HKP-16657$14.95 -
PTR HK 91/G3 (7.62x51/.308) Receiver Flat
PTR
$99.95HK 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...HKP-02320$99.95 -
HKP Picatinny Rail For HK Receivers - 17 Slot
HKP HK Parts
$69.95HKP 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...HKP-01446$69.95 -
DTAC 90 Series Semi Auto Shelf Weldment - Billeted
DTAC Dakota Tactical
$34.95DTAC Spec Billeted Semi Auto Shelf For C/P'ed Trigger Group -Dakota Tactical The needed receiver shelf that is welded to the magwell of the receiver to allow the use of clipped & pinned trigger housings. These are as made to DTAC's custom specs...HKP-18072$34.95 -
HKP MP5 Sling Clip for Magwell
HKP HK Parts
$9.95HKP MP5 Sling Clip for Magwell This is the factory correct sling clip that attaches to the left hand side of the magwell. Note: 3 rivets are required to attach - sold separatelyHKP-18313$9.95 -
HKP Spare Buffer For Folding Stocks & End Caps
HKP HK Parts
$9.95HKP Spare Buffer For Folding Stocks & End Caps New US manufactured flat style "H"buffer to replace the factory HK buffer on MP5K folding stocks and end caps. As well as a spare or replacement buffer for the MP5 & MP5K folding B&T stocks. Made...HKP-17886$9.95 -
HKP HK MP5 .22 Sling Clip Kit - Black
HKP HK Parts
$24.95HKP HK MP5 .22 Sling Clip Kit - Black Each unit will fit all models of the MP5 .22 that have the 3 mounting holes on the left side of the magwell. This item installs in a few mins and comes complete with all you need for the install. With the addition of...HKP-15706$24.95 -
HKP Flat Bending Billeted Jig Set For All HK Style Flats
HKP HK Parts
$449.95HKP Flat Bending Billeted Jig Set For All HK Style Flats NEW LATEST 4th GENERATION VERSION AND DESIGN. THE FINEST JIG SET AVAILABLE! Billeted universal flat bending jig for all HK receiver flats including our new PTR .308 flats and the...HKP-19583$449.95 -
LSC MP5 9mm Receiver Flat
LSC
$199.95MP5 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...HKP-20555$199.95 -
HKP MP5 Sling Clip Rivet Set - 3 Rivets
HKP HK Parts
$7.89HKP MP5 Sling Clip Rivet Set - 3 Rivets Factory correct MP5 sling clip rivet set (includes a set of 3 rivets). This is the factory correct rivet set to attach the HK sling clip to the left hand side of the magwell. Each set includes a set of 3 rivets for...HKP-17003$7.89 -
HKP Picatinny Rail For HK Receivers - 13 Slot
HKP HK Parts
$52.95HKP Picatinny Rail For HK Receivers - 13 Slot Mil-Spec all steel CNC'ed picatinny rail in the white, relief cut to fit flush and low profile on HK receivers. The most solid and consistent mounting platform made for mounting scopes and optics to HK builds...HKP-18238$52.95 -
Out Of Stock
HKP HK MP5 9mm Receiver Flat with Weldment Set
HKP HK Parts
$219.95HKP HK MP5 9mm Receiver Flat with Weldment Set New MP5 receiver flat and weldment set combined for the best complete build option on the market. Made by the original German tool and die maker of the LSC receiver flat utilizing factory original German...HKP-20920$219.95 -
HKP MP5/HK94 Complete Weldment Set For Receiver Flat
HKP HK Parts
$59.95HKP MP5/HK94 Complete Weldment Set For Receiver Flat This is the finest, most correct weldment set for your HK MP5, 94 project available. Each Weldment Kit Contains: 1x Semi Auto Shelf Hanger Block 1x Rear stock bushing 1x Scope mounting piece 1x...HKP-01453$59.95 -
HKP Picatinny Rail For HK Receivers - 15 Slot
HKP HK Parts
$59.95HKP Picatinny Rail For HK Receivers - 15 Slot Mil-Spec all steel CNC'ed picatinny rail in the white, relief cut to fit flush and low profile on HK receivers. The most solid and consistent mounting platform made for mounting scopes and optics to HK builds...HKP-18241$59.95 -
PTR HK MP5 Flat Receiver w/ Weldment Set
PTR
$294.95MP5 9mm Receiver Flat With Complete Weldment & Rivet Set - PTR/LSC Several years ago PTR bought out LSC and now owns the tooling and dyes for the LSC 9mm flats. These elusive flats have been hard to find and are now available for the first time here...HKP-19509$294.95 -
HKP MP5K Enhanced SD Shroud
HKP HK Parts
$119.95MP5K SD Shroud For SP89 & MP5K Conversion Our MP5K SD shroud is a the best option for those who want to build a custom MP5K SD model. Made in the USA.HKP-00849$119.95 -
H&K Magazine Catch - MP5, MP5K - Latest Style
H&K Heckler & Koch
$64.95H&K Magazine Catch - Latest Style Genuine HK mag release for factory and clone firearms. This component often resolves issues with mags not locking into position on HK clones and builds. Constructed from a single piece of steel unlike the...HKP-00911$64.95 -
Flat Bending Jig Set For All HK Style Flats - Billeted - All Steel
$599.95Flat Bending Jig Set For All HK Style Flats - Billeted - All Steel NEW- LATEST 4th GENERATION 100% ALL STEEL VERSION AND DESIGN. THE FINEST JIG SET AVAILABLE! All steel billeted universal flat bending jig for all HK receiver flats including our new...HKP-19595$599.95 -
RCM MP5 9mm Trunnion
RCM
$64.95RCM MP5 9mm Trunnion US made to exact factory HK specifications and machined completely from ordnance grade steel and heat treated to factory specs. Compatible With: MP5, 94 MP5K SP89 Clones or other custom buildsHKP-01193$64.95 -
Out Of Stock
HKP Semi Auto Shelf for Receiver - Billeted
HKP HK Parts
$17.95HKP 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...HKP-21470$17.95 -
HKP 90 Series Paddle Mag Release Easy Install Fixture
HKP HK Parts
$187.95HKP 90 Series Paddle Mag Release Easy Install Fixture The original one and only paddle mag release fixture. The perfect jig for the installation of the factory correct paddle mag release with the proper hole placement and an easy to use jig that will...HKP-17587$187.95 -
HKP SP5K 9mm Drop In Paddle Mag Release Upgrade Kit
HKP HK Parts
$74.95HK SP5K Anti-Rattle Roller Tipped "Paddle" Magazine Release Install Kit No modifications, no refinishing...complete drop-in kit included. New USA made busing for a drop-in install kit for the HK SP5K. This kit will allow any end-user to quickly,...HKP-18192$74.95 -
H&K HK MR556 Rear Lower Receiver Locking Pin
H&K Heckler & Koch
$79.95HK MR556, MR762 Locking Pin With Spring Loaded Detent This is the rear takedown pin with ball detent and locking mechanism installed. The idea behind this type of system is to decrease the movement of the upper and lower receivers and improve the...HKP-02672$79.95 -
H&K HK MR556/416 Ejection Port Cover - Black
H&K Heckler & Koch
$34.95HK German HK 416, MR556 Ejection Port Cover HK manufactured newer polymer style cover assembly found on the latest HK 416 & MR556. This item can also be used on other AR15-style projects to enhance the project with the finest ejection port cover...HKP-15229$34.95 -
Out Of Stock
H&K HK MR556/416 Ejection Port Cover Door Assembly
H&K Heckler & Koch
$71.95HK German HK 416, MR556 Ejection Port Cover Door Assembly Complete This is the newer polymer style cover found on the latest HK 416 and MR556's. This is the complete ejection port door assembly needed on all AR15 or MR556/HK416 models. Can also be used...HKP-16951$71.95 -
Out Of Stock
HKP Semi Auto Shelf, Hanger Block For Receiver
HKP HK Parts
$13.95HK Semi Auto Shelf Weldment, Hanger Block Weldment 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...HKP-17572$13.95 -
H&K HK MR556/416 Receiver End Plate
H&K Heckler & Koch
$24.95HK 416, MR556 End Plate For Receiver & Buffer Tube New HK German manufacture. Compatible With: HK MR556 & HK 416 upper receiver/buffer tubesHKP-16603$24.95 -
H&K HK MR556/MR762 Receiver Take Down Tool
H&K Heckler & Koch
$19.95HK MR556 & MR762 Take Down Tool For The Upper & Lower Receiver This part is the tool used to tighten down the stock movement on the E1/E2 stock. Each tool will be stored in the rear of the E1/E2 stock. Please Note: We get...HKP-02653$19.95 -
LSC/PTR Receiver Flat- MP5 9mm
LSC
$239.95MP5 Receiver Flat - PTR/LSC New PTR 9mm Receiver Flat made on the original LSC tooling. This flat is considered by many to be the most sought-after HK flat available on the market and perfect for that HK custom build. This item is not considered an FFL...HKP-01431$239.95 -
H&K HK416 A5 Factory German Extended Castle Nut
H&K Heckler & Koch
$71.95H&K HK416 A5 Factory German Extended Castle Nut Original HK Factory German steel 416 A5 Extended Castle Nut. Perfect for MR556, HK 416 A5 builds, or upgrades.HKP-19164$71.95 -
H&K MP5K/SP89/SP5K 9mm End Cap
H&K Heckler & Koch
$99.95HK Factory German MP5K, SP-89, & SP5K End Cap With Sling Swivel Each pistol end cap is OEM HK German MP5K and MP5K-N and has the HK German factory buffer. Compatible With: MP5K SP89 SP5K MP5K-N MP5K-PDW MP5K Clone Or Other Custom BuildsHKP-00394$99.95 -
HKP HK MP5K QD End Cap with Buffer - Black
HKP HK Parts
$44.95Quick Detach MP5K, SP-89 Steel End Cap With Replaceable Rubber Buffer Compatible With: MP5K SP89 Clone or other custom buildsHKP-20117$44.95 -
HK G36/SL8 (5.56/.223) Factory Recoil Buffer
USA
$16.95HK G36 Or SL8 Factory Recoil Buffer A must have spare part as the buffer is prone to wear and breakage. Compatible With: All HK G36 models SL8 models ClonesHKP-18541$16.95 -
RCM HK G3, HK 91, PTR Trunnion
RCM
$64.95RCM Trunnion For The HK91/G3 Series - US Made This part is machined from ordnance grade 9310 enhanced steel and heat treated to exact HK specifications. This item is the best USA-made trunnion on the market. Machined to spec and are to the custom ground...HKP-01289$64.95