Interesting case. The shot gun in question is a short shotgun, ie sawed off and therefor requiring registration under the 1934 act. The antique exemption comes under the 1968 act. The opinion draws heavily, if not almost exclusively, on the National Firearms Act USC 5801-72, which is under the IRS. This leaves considerable ambiguity about whether the case is about antique long guns, as generally bought, sold, and used for sporting purposes by the good folks on this board, or sawed off guns, generally shunned for sporting purposes.