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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HK416 OTB E1 Buttstock and Buffer Tube Set
H&K Heckler & Koch
$469.95H&K MIL-SPEC 416 OTB Buffer Tube & HK E1 Stock Combo Genuine HK416 E1 Stock with the new style marine environment "over the beach" buffer tube. Buffer tube has ball bearing rollers to tighten the stock when locked in position, and helps smooth...HKP-20104$469.95 -
HK MP5 Trunnion - .40 S&W, 10mm
HKP HK Parts
$139.95MP5 40 & MP5 10mm Trunnion Machined from ordnance-grade steel and heat-treated to factory specs. Each has the bullet guides pre-installed and included. These are the best USA-made trunnions on the market. Machined to HK spec, making the installation...HKP-02737$139.95 -
On Sale
AR-15 Commercial Buffer Tube
HKP HK Parts
Now: $16.95Was: $24.95AR-15 Commercial Buffer Tube Compatible With: All AR-15 style platforms Not correct length for HK rifles Features: Made From T7 7075 Aircraft grade aluminum Made in the USA 6 Position Each features a highly polished inside tube Black...HKP-02728Now: $16.95Was: $24.95 -
HK MP5K, SP89 Flat Receiver - 9mm
HKP HK Parts
$199.95MP5K, SP89 Receiver Flat - 9mm New MP5K receiver flat made by the original German tool and die maker of the LSC receiver flat utilizing factory original German prints and specifications. The creator of our receiver flat has been regarded as the premier...HKP-20733$199.95 -
HK416, MR556 Buffer Tube - Enhanced - Commercial
H&K Heckler & Koch
$249.95HK 416, MR556 OTB (over the beach) Buffer Tube, Receiver Extension - Commercial: Genuine HK German manufactured 416, MR556 new style latest generation marine environment & over the beach buffer tube. Each Commercial buffer tube has built in drainage...HKP-15424$249.95 -
HK91, G3 Magazine Release Set, Complete - USED
H&K Heckler & Koch
$24.95Heckler and Koch Magazine Release Set (Left to Right) for HK91 and G3 This HK German manufactured, used magazine release set for HK .308 pattern rifles consists of 6 pieces. Complete left-to-right mag catch assembly with both push-button and paddle...HKP-22466$24.95 -
HK G36, SL8 Paddle Magazine Release
H&K Heckler & Koch
$19.95Heckler and Koch Paddle Magazine Release for HK G36 and HK SL8 Compatible With: SL8 G36 G36K G36CHKP-02152$19.95 -
HK G36, SL8 Cocking Handle Spring
H&K Heckler & Koch
$10.95HK German G36 Cocking Handle Spring - All Variants Compatible With: G36 - all variants SL8 - all variantsHKP-01862$10.95 -
HK MP5, MP5K Sling Attachment Weldment - Ambi - Front End
HKP HK Parts
$14.95HKP Front Sight Tower Ambi Sling Attachment Weldment Ambi sling loop that is welled and installed on all MP5F model front sight tower. A great upgrade for that custom build or for those that want to have the ability to have an ambidextrous sling loop at...HKP-17881$14.95 -
HK G3 Rear Receiver Section with Rear Sight - Complete - Parkerized - SURPLUS
H&K Heckler & Koch
$54.95H&K G3 Complete Parkerized Rear Receiver Section w/ Rear Sight - SURPLUS UNIT QUALITY MAY VARY - SEE PHOTOS FOR EXAMPLE OF CONDITION RANGE Sold Individually Genuine H&K parkerized steel rear receiver section with fully installed G3 rear sight...HKP-22164$54.95 -
HK416, MR556 Charging Handle Roll Pin
$7.95HK 416, MR556 Roll Pin for Charging Handle - HKP This is the shorter one that is used on the inside of the charging handle. There are two of these pins used per charging handle.HKP-16536$7.95 -
HK G36, SL8 Cocking Handle Spring - US
$9.95G36 Cocking Handle Spring- US Made Compatible With: G36 All variants SL8 All variantsHKP-18369$9.95