A virgin receiver is a virgin receiver. It can be built into a pistol if it is truly virgin or it can be built into an AOW or a long gun. Once a long gun it cannot be made into an AOW. Pistols can be made into AOW's and virgin receivers can be made into AOW's. An SOT can register and engrave a virgin or pistol receiver into AOW status and file a form 2 with the ATF and file paperwork for a form 4 to an individual and the AOW will transfer with the $5 tax or an individual can file a form 1 with a pistol or virgin receiver and pay $200 and get it engraved once approved.