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.
- Product
- Qty in Cart
- Quantity
- Price
- Subtotal
-
HK UMP, USC Lower Locking Pin
H&K Heckler & Koch
$36.95HK German UMP Lower Locking Pin For use with all HK UMP lowers and USC to UMP conversions. New HK German manufacture.HKP-00595$36.95 -
HK91, G3 Magazine Catch
H&K Heckler & Koch
$19.95G3 Magazine Catch High-quality HK German production units are brand-new. These also have the proper newer style cut in them and round shafts. Compatible With: HK G3 HK91 PTR91HKP-02073$19.95 -
HK416, HK417, MR556, MR762 Bridge
H&K Heckler & Koch
$24.95H&K HK 416/417/MR556/MR762 Bridge For Lowers Compatible With: HK MR556 HK 416 HK MR762 HK 417HKP-02676$24.95 -
HK416 E1, MR556 Charging Handle - RAL8000
H&K Heckler & Koch
$169.99New RAL 8000 HK Designed HK416, MR556 Ambidextrous Charging Handle (E1). The E1 HK 416 FDE charging handle release latch has the ability of being swapped from the left side (E1) to the right sight (E2) with simple tools. HK's own design boasts a smooth...HKP-18502$169.99 -
MR556 A4 Upper Receiver Kit - 16.5″ - 5.56 - M-LOK
H&K Heckler & Koch
$1,939.00H&K MR556 A4 16.5″ 5.56 M-LOK Upper Receiver Kit This kit includes a complete upper receiver/barrel assembly, allowing Mil-Spec 5.56mm AR-style rifles to be retrofitted to HK’s piston and pusher rod system. This system utilizes a piston...HKP-21909$1,939.00 -
HK MP5K, SP89, SP5K Trunnion - 9mm - RS
RCM
$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-02242$69.95 -
HK21, FMP21 Teardrop Rail Set - T-Rail
HKP HK Parts
$197.95HKP HK21/FMP21 Teardrop Rail Set HK teardrop style reinforcement rails. The ultimate choice for period correct builds. Expertly crafted in the USA from high-quality 4140 steel, these ready-to-weld rails are engineered for precision and durability...HKP-21671$197.95 -
MP5K Complete Weldment Set
$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-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 and hassle free. The way a custom HK build it should...HKP-20807$65.00 -
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 -
HK MR556 A4 Upper Receiver Kit - 11"- M-LOK
H&K Heckler & Koch
$1,998.95H&K Heckler & Koch MR556 Upper Receiver Kit A4 -11″ - M-LOK This kit includes a complete upper receiver/barrel assembly, allowing Mil-Spec 5.56mm AR-style rifles to be retrofitted to HK’s piston and pusher rod system. This...HKP-21910$1,998.95 -
HK417, MR762 Castle Receiver Extension Nut for Buffer Tube
H&K Heckler & Koch
$44.95H&K HK MR762/417 Castle Receiver Extension Nut For Buffer Tube - Black New HK German manufacture and the factory correct offering with the proper installation screws and staking guides. Compatible With: HK MR762 HK 417HKP-16768$44.95