Did the outside of Oswald's package have any indication that a rifle was within?
Assuming that the rifle that A J Hidell ordered was delivered completely assembled and the packaging/box said Klein's Sporting Goods as the addressee...would have been indicative. It could have contained a pair of stilts or a pogo stick.
I think that similar rifle packaging should have been obtained and entered as evidence.
But still...Hidell would be a tough name to not remember.