Ok so I bought a Draco pistol a while back with intentions to sbr it. I was just going to drill and tap the rear trunnion and add a DPH stock or something myself, but then I found out you have to have it engraved first and cant find anyone in town to do it so I figured Ill just have a pro do it during a build or something. Now this is where im confused. I filled out a ATF Form 5320.1 (aka Form 1) — Application to Make and Register a Firearm, used to make an NFA item. But if someone else is going to be working on it, will the form 1 work or will I need to fill out a ATF Form 5320.4 (aka Form 4)