Gordon Van Gilder, a 72-year-old retired schoolteacher in New Jersey, faces a 10-year prison sentence for possessing an unloaded 18th-century flintlock pistol in his car. Mr. Van Gilder, a collector of 18th-century memorabilia, said he had the gun unloaded and wrapped in a cloth in the glove compartment of his vehicle when he was pulled over in November by a Cumberland County sheriff’s deputy for a minor traffic violation, according to a video posted last week by NRA News. After consenting to a search of his vehicle, Mr. Van Gilder said he alerted the deputy of the pistol in his...