You could build an auto burglar out of a auto burglar but it couldnt have the original barrels on it. To register a nfa weapon you have to be the manufacturer of it. An auto burglar that no longer has its barrels is just a receiver and could be mated with some barrels(not the original) and registered by a class2. If the original barrels were on the gun a strong case could be made that you were in possesion of an unregistered weapon and that you registered it even though you were not the manufacturer.
Be careful what you talk about on an open forum. It would be considered unlawful to possess an unregistered short barreled shotgun or a registered one without a proper transfer.
