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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HK91, G3 Magazine Catch
H&K Heckler & Koch
$19.95Heckler and Koch Magazine Catch for HK G3 and HK91 High-quality HK German production units are brand-new. These also have the proper newer style cut in them and round shafts. Compatible With: HK91, G3 PTR91HKP-02073$19.95 -
On Sale
HK MP5K, SP89, SP5K Trunnion - 9mm - RS
RCM
Now: $58.95Was: $69.95MP5K Reverse Stretch Trunnion US-made to exact factory HK specifications for the HK MP5K, SP89 9mm builds. There is a difference between the MP5K and the MP5 trunnion. This offering is the correct trunnion for the MP5K and all MP5K PDW variants,...HKP-02242Now: $58.95Was: $69.95 -
HK G36, SL8 Cocking Handle Axle Pin
H&K Heckler & Koch
$11.95HK German G36 & SL8 Cocking Handle Axle Pin This is the rivet pin that is used to attach the swiveling cocking handle to the body of the carrier. These can be replaced as they break and wear. Compatible With: HK G36 HK SL8HKP-01877$11.95 -
HK417, MR762 Magazine Catch Spring
H&K Heckler & Koch
$9.95Heckler and Koch Magazine Catch Spring for HK417 and HK MR762 New HK German manufacture. Factory correct magazine catch for the magazine release. Compatible With: HK417, MR762 G28HKP-16520$9.95 -
On Sale
HK21E, HK23E Rear Sight Base
HKP HK Parts
Now: $30.95Was: $38.95HKP HK Parts Rear Sight Base for HK21E, HK23E US manufactured billeted from solid ordnance grade bar stock. Each unit is precisely machined to factory tolerances. Requires post installation machining to accommodate a scope. Compatible...HKP-21467Now: $30.95Was: $38.95 -
On Sale
HK G36, SL8 Paddle Magazine Release
USA
Now: $13.95Was: $17.95US Magazine Paddle Release for HK G36 and HK SL8 HK G36 Mag Release or mag catch. Compatible With: SL8 G36 G36K G36CHKP-18222Now: $13.95Was: $17.95 -
Out Of Stock
HK MR556 A4 Charging Handle - Ambi
H&K Heckler & Koch
$199.95H&K HK MR556 A4 Ambi Charging Handle Upgrade your MR556 or HK416-style rifle with this factory H&K ambidextrous charging handle, designed for smooth, reliable operation from either side. Built to Heckler & Koch’s exacting standards,...HKP-21933$199.95 -
On Sale
HK MP5K Weldment Set, Complete
Now: $50.95Was: $59.95MP5K Complete Weldment Set Each set of weldments is all of the weldments required for an MP5K flat. Includes: Rear sight base Sight tab Case deflector Semi auto shelf Side reinforcement tabs 2 X rear stock bushingsHKP-16231Now: $50.95Was: $59.95 -
On Sale
HK93 Trunnion
RCM
Now: $54.95Was: $65.00RCM HK93 Trunnion Made to exact factory HK specifications for the HK93, HK33 type builds. These are the best trunnions of their kind on the market. Machined to HK spec making the install painless and hassle free. The way a custom HK build it should...HKP-20807Now: $54.95Was: $65.00 -
HK416, MR556 Magazine Catch - Ambi
H&K Heckler & Koch
$104.95Heckler and Koch Ambidextrous Magazine Catch for HK416 and HK MR556 Factory HK ambi magazine catch, release. Compatible With: HK416A5, MR556 A4 NOT compatible with earlier variants with single-side controlsHKP-22289$104.95 -
HK416, MR556, HK417, MR762 Takedown Pin - Rear - A4 Style
H&K Heckler & Koch
$47.95H&K MR556, HK416, HK417, MR762 Rear Takedown Pin Factory A4 rear takedown pin. Will work for A1 and A4 applications. Compatible With: HK MR556 A1 and A4 HK416 HK MR762 A1 and A4 HK417 AR-14, M4, M16HKP-22029$47.95 -
HK417, MR762 Buffer Tube Castle Nut
H&K Heckler & Koch
$44.95Heckler and Koch Castle Nut for Receiver Extension for Buffer Tube for HK417 and MR762 New HK German manufacture and the factory correct offering with the proper installation screws and staking guides. Compatible With: HK417, MR762HKP-16768$44.95