What exactly is a take off receiver?
What a lot of people will do is buy a gun cheap and part it out. Often times, they are worth more as parts, especially barrels lately. Usually what is leftover is the receiver, and they might call it a "take off" when more specifically, parts are taken off of IT.

A bare or loaded receiver technically IS a gun legally, and is usually sold very cheaply because the new buyer (if in a different state or one that requires a BGC) will have to go through the hassle of a transfer OR be an FFL with parts to build it. A common receiver is often just stripped for parts (like you need) then destroyed and scrapped. Or given back at a gun buyback...
BTW, Welcome Aboard!
