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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HK45, USP Spring - Flat Sear - Match - Enhanced
H&K Heckler & Koch
$9.95Enhanced Match Flat Sear Spring The nickel-plated sear spring is also regarded as a "match" flat spring as it will improve the feel and "smoothness" when pulling the trigger as it takes up some of the gritty feel. It is a must-have upgraded part to...$9.95 -
HK MP5 Replacement Buffer - 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)$3.49 -
HK Stock Pin Bushing Weldment
HKP HK Parts
$3.95HK 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...$3.95 -
HK Pin - Barrel - Retaining - 5mm - Standard Size
H&K Heckler & Koch
$9.95H&K HK Pin - Barrel - Retaining - 5mm - Standard Size Barrel Retaining Pin Each barrel pin is used for installing a new or replacement barrel. HK suggest using a new factory barrel pin when installing or reinstalling a HK barrel. We also offer the HK...$9.95 -
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...$9.89 -
HK94, MP5 Case Deflector Rivet
HKP HK Parts
$1.95HKP 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...$1.95 -
HK MP5 Handguard - M-LOK - Extended Picatinny Mount
UTG PRO
$199.95 - $239.95UTG HK MP5 PRO Handguard with Extended Upper Picatinny Mount - M-LOK Made in the USA. Compatible With: HK MP5 HK94 SP5 AP5 MAC-5 clones may require custom fitment. Modified components are not eligible for return. In-spec clones & custom...$199.95 - $239.95 -
HK VP9, VP40 Trigger - F3 - Full Flat Face - 9mm / .40 S&W
Lazy Wolf
$129.95Lazy Wolf's F3 Full Flat Face Trigger for the extensive HK VP Series - Black In a collaboration with Lazy Wolf Guns, HK Parts is offering aftermarket triggers for your HK VP9 and VP40 handguns. The drop in VP9 series trigger is the best trigger ever...$129.95 -
HK Oversized Barrel Retaining Pin - 5.25mm
H&K Heckler & Koch
$9.95H&K Oversized Barrel Retaining Pin - 5.25mm This is the barrel pin used for installing a new or replacement barrel. HK suggests using a new factory barrel pin when installing or reinstalling an HK barrel in the trunnion. Each pin is slightly...$9.95 -
HK91, G3 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 transfer is required as this is an un-folded flat. Compatible...$166.95 -
Out Of Stock
HK USPC, P2000 Magazine - Flat Floor Plate - 9mm
H&K Heckler & Koch
$22.95H&K HK USPC/P2000 9mm Magazine Flat Floor Plate USPC 9mm 13 round flat floor plate for the 9mm UPSC and P2000 magazine. This is a Heckler and Koch genuine part. Perfect for concealed carry or for a lower profile Compatible With: HK USP Compact 9mm...$22.95 -
HK91, G3 Receiver Flat - US Made
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...$99.95