WW2 Armory LLC HK21 Semi-Auto Build Services

HK21 Semi Auto Build By WW2 Armory

Convert your HK21 FMP Parts Kit to a finished, professional HK21 Semi-auto. 

Full kit inspection & documentations: We visually inspect your FMP kit upon arrival, confirm components, document photos of condition, and establish a work order.

Complete assembly & fitment: Skilled welding of the receiver. test fit bolt group, feed mechanism, Barrel and all mating pieces. (all semi-builds are tested in full auto with a post sample trigger pack)

Finished: Cerakoting Black. (other colors available)

Standard post-build warranty: 60-day limited workmanship warranty on assembly work (user damage, misuse, and normal usage excluded).

Laser Engraving: Custom Laser Engraving Available. 

If you have an FFL  and are wanting Variance Marking We will only make variance or full-auto conversions if the customer presents paperwork on correct licensure (FFL/SOT/Class 2 certification) all builds will only take place with stringent adherence to NFA and ATF laws. 07/SOT You will need to send authorization paperwork on NFA firearms.

What we ask of you:
Your complete FNP parts Kit shipped to our store with 16" or longer barrel (ship at risk; insured shipping also recommended).
License documentation (if seeking variance or full-auto conversion) copy of FFL/SOT.
Clear build instructions or selection from our standard build options (we’ll confirm any special requests on receipt).
Payment by invoice (deposit available on custom pieces or ordered parts).
We adhere to all relevant federal, state, and local legislation. Full-auto modifications, transfers in NFA status, and receiver builds that must be serialized will only be done on duly licensed businesses and in full accordance with laws of the ATF. It will always remain the customer's job to make sure that the completed firearm is legal in its state. We will have no acceptance of builds or parts that are prohibited to own or transfer.

Turnaround, shipping & liability
Lead times and ready date change frequently (14 days as if Oct 2025) Call to latest turnaround times. 
Sending to and from our store is the buyer's responsibility unless otherwise ordered. We suggest that you insure the shipping.
We do not accept liability for kits lost in transit before reaching us; units upon arrival, immediately after arrival, get inspected and any discrepancy noted.

Documentation: We photograph, document, and sign off on each build, to insure quality and safety. 

How to order:
Send us your photos and brief message regarding your FNP kit and any personal requests. Sales@ww2armory.com or 904-571-5712 
Attach a copy of your FFL/SOT in case you require variance or full-auto orders. We shall then submit to you an estimate in writing, possible upgrades and an invoice to secure your job with us.

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