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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Out Of StockOn Sale
HK 416, R556 Castle Nut - A5 Style - Extended
HKP HK Parts
Now: $31.96Was: $39.95HK 416, MR556 A5 Style Extended Length Castle Nut Unlike the factory German A5 castle, our A5 extended buffer tube castle nut is compatible with both mil-spec & commercial buffer tubes. Crafted from ordnance grade steel and nitrided for a...Now: $31.96Was: $39.95 -
Out Of StockOn Sale
HK Picatinny Rail For HK Receivers - 15 Slot
HKP HK Parts
Now: $47.96Was: $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...Now: $47.96Was: $59.95 -
On Sale
Picatinny Rail for HK Receivers - 13 Slot
HKP HK Parts
Now: $42.36Was: $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...Now: $42.36Was: $52.95 -
On Sale
HK UMP, USC 9mm / .40 S&W / .45 ACP Enhanced Top Receiver Rail
HKP HK Parts
Now: $39.96Was: $49.95HK USC & UMP Top Receiver Rail With Hardware - US Made The extended length allows the use of all optics that fit on a Picatinny rail. This unit has a contoured, no-snag design for ease of use and a beautiful fit. Made from billet machined aluminum...Now: $39.96Was: $49.95 -
HK416, MR556 Buffer Tube - Mil-Spec
HKP HK Parts
$29.95Mil-Spec US-Made Buffer Tube Compatible With: HK416 HK MR556 All AR-15 style platforms Features: Made from T7 7075 aircraft grade aluminum 6-position Made in the USA Each features a highly polished inside tube Black mil-spec triple hard coat teflon...$29.95 -
On Sale
UZI Lower with Grip Complete
IMI
Now: $89.95Was: $99.95Uzi Lower Complete - IMI Manufactured For The German Military Surplus IMI Manufactured Uzi Grip (lower) complete with all internals as shown. Each lower comes complete with all internals, grips and mag release assembly installed. Perfect for spare parts...Now: $89.95Was: $99.95 -
On Sale
HK417, MR762, G28 Wrench - Buffer Tube
HKP HK Parts
Now: $23.96Was: $29.95HKP HK MR762/417/G28 Buffer Tube Wrench The perfect metric wrench to remove and install the MR762 & G28 castle nuts on the buffer tube. A perfect addition to have on hand for G28 buffer tube upgrades, etc. Made from all steel, heat treated and made...Now: $23.96Was: $29.95 -
On Sale
HK MP5, HK94 Complete Weldment Set For Receiver Flat
HKP HK Parts
Now: $47.96Was: $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...Now: $47.96Was: $59.95 -
Out Of StockOn Sale
HK Receiver Flat Bending Jig Set - Billet Steel
HKP HK Parts
Now: $479.96Was: $599.95Flat Bending Jig Set For All HK Style Flats - Billeted - All Steel All steel billeted universal flat bending jig for all HK receiver flats including PTR .308 flats and the PTR/LSC flats. Each bending jig comes complete with all the pieces you need for...Now: $479.96Was: $599.95 -
On Sale
HK MP5 Receiver Flat with Weldment Set - 9mm
HKP HK Parts
Now: $175.96Was: $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...Now: $175.96Was: $219.95 -
On Sale
HK416, MR556 Ejection Port Cover
H&K Heckler & Koch
Now: $49.46Was: $54.95H&K HK MR556/416 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...Now: $49.46Was: $54.95 -
On Sale
HK416, MR556, MR762 Buffer Retainer Pin
H&K Heckler & Koch
Now: $3.56Was: $3.95H&K HK MR556/MR762/416 Buffer Retainer Pin Compatible With: HK MR556 HK 416Now: $3.56Was: $3.95