Can the government establish the interstate commerce element in a § 922(g) prosecution by showing that a single interchangeable part of a firearm traveled across state lines or does the government have to show that an entire firearm traveled across state lines?

Where the defendant genuinely, but mistakenly, believed that his civil rights had been restored within the meaning of 18 U.S.C. § 921(a)(20), can the government meet its burden of proof by showing that his rights had not, in fact, been restored, or must it prove that he knew they had not been restored?

Can the government establish the interstate commerce element in a § 922(g) prosecution by showing that a single interchangeable part of a firearm traveled across state lines or does the government have to show that an entire firearm traveled across state lines?