I'm curious. I thought a stripped lower receiver was already considered an AOW? Last time I bought one it was marked on the paper work that way. Similar to how the 14" barrel shotgun is legal when made oal 26". Not registered as shotgun but AOW. Is this something different?
You are mixing apples and oranges
Title 1 guns (regular rifles, shotguns, handguns, etc..) are listed on the 4473 as long gun, handgun or other (stripped receiver or frame).
An AOW (Any Other Weapon) is a title 2 (NFA) weapon in the same category as MG's, SBR/SBS's, Suppressors and DD's. They require an NFA form 1 to build or a form 4 to transfer. Here is the definition of an AOW https://www.atf.gov/firearms/qa/what-does-“any-other-weapon-mean
In other words, they are 2 totally different things.