The form 4 is only used to transfer an NFA item, tax paid. What you would fill out and file if you were buying a completed gun from a dealer or individual. Since you are making the thing, the form 1 and supporting items (fingerprint card, statement) are all you need to fill out and send in. Write ATF and get the "package", they will send you the proper forms you need. the fingerprint form is "standard" , but the one you get from ATF will already be filled out with the proper "originating agency" filled in as needed. Your local PD will have a blank form. Wrong info, it won't get processed.