According to The Hill
, the NSA "acknowledged that it collects records on virtually all U.S. phone calls." The NRA and ACLU see tyranny in this. Because Section 215 of the Patriot Act is understood to allow the NSA to collect records that are considered "relevant" to terrorism, the NRA fears the surveillance program is especially being used to listen to calls to gun stores, shooting ranges, and even the NRA and other gun rights groups.
Moreover, the NRA claims the government's reading of Section 215 allows them to "simply demand the periodic submission of all firearms dealers' transaction records, then centralize them in a database indexed by the buyers' names for later searching."
Between the phone data surveillance and the firearms dealers' transaction records, creating a gun registry could potentially be quite easy for the federal government.