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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On Sale
HK21E, HK23E Rear Sight Base
HKP HK Parts
Now: $24.83Was: $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...HKP-21467Now: $24.83Was: $38.95 -
HK MP5K Weldment Set, Complete
$59.95MP5K Complete Weldment Set Each set of weldments is all of the weldments required for an MP5K flat. Includes: Rear sight baseHKP-16231$59.95 -
HK93 Trunnion
RCM
$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...HKP-20807$65.00 -
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...HKP-16768$44.95 -
HK G36, SL8 Recoil Spring Assembly, Complete
H&K Heckler & Koch
$69.95Recoil Rod Assembly for HK G36 & SL8 New HK factory German G36/SL8 (fits all variants of SL8/G36) recoil rod assembly complete. Great for replacement or for a spare as these have been hard to find.HKP-01057$69.95 -
HK UMP Magazine Release - Enhanced - Billeted
HKP HK Parts
$34.95HKP HK Parts Enhanced Paddle Magazine Release for HK UMP 9mm, .40 S&W, .45 ACP This is a very common replacement part as they are fairly easy to break on the UMP lower. With this new mag release,...HKP-18758$34.95 -
HK MP5 Paddle Magazine Release Lever - .40 S&W, 10mm
HKP HK Parts
$59.95HKP HK Parts Magazine Release Lever for .40 S&W and 10mm HK MP5 Compatible with MP5HKP-01274$59.95 -
Out Of Stock
HK416, MR556, MR762, AR-15 Take Down Pin Set - Titanium
HKP HK Parts
$29.95AR15, M4, MR556, MR762, AR10 Enhanced Take Down Pin Set Front & Rear - Titanium Custom ultra strong pure titanium front and rear take down pin set. Each set included both the front and rear pins for...HKP-17936$29.95 -
HK417, MR762 QD End Plate - Flush Cup
H&K Heckler & Koch
$174.95H&K HK MR762/417 Flush Cup QD End Plate Factory HK flush end cap with dual QD sockets for ambidextrious sling attachment. Compatible With: HK MR762HKP-21642$174.95 -
Out Of Stock
HK MR556 Upper Receiver Kit -16.5" - M-LOK
H&K Heckler & Koch
$1,779.95New HK Factory German MR556 Upper Kit with M-LOK forearm Includes: Complete MR556 upper receiver with M-LOK forearm MR556 Bolt group Complete Tungsten FilledHKP-17366$1,779.95 -
HK417, MR762 Takedown Pin - Front - A4 Style
H&K Heckler & Koch
$43.99H&K MR762 A4 Receiver Front Takedown Pin German-made factory pivot pin for the MR762 A4. Will work with A1 models as well.HKP-21958$43.99 -
On Sale
HK G36, SL8 Cocking Handle Axle Pin - USA
USA
Now: $6.98Was: $10.95HK G36, SL8 Cocking Handle Axle Pin - US Made 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...HKP-18367Now: $6.98Was: $10.95