You have to purchase the suppressor first, the serial number, mfg, and model have to be on the form 4. I have just sent my form to my county Sheriff's office for his signature. Fortunately, I have a gun friendly Sheriff. As long as you pass a quick background check, he willingly signs off. BTW I live in Tarrant county, Texas, for those who may be interested in making a NFA purchase and wondering which way to go.rushca01 said: