Today, the U.S. Court of Appeals for the Sixth Circuit decided Hardin v. BATF, concluding that a bump stock is not a machine gun "part" prohibited under federal law. Judge Gilman wrote for the court, joined by Judge McKeague. Judge Bush concurred in the judgment.
Here's how Judge GIlman summarizes the court's conclusions:
The placement of a bump stock on a semiautomatic rifle causes the rifle to function essentially like a machinegun by dramatically increasing the rate of fire. And the possession of a machinegun is a criminal offense under the Gun Control Act of 1968. This raises the question of whether a bump stock is a machinegun "part" as defined by the National Firearms Act of 1934. The question is a close one on which reasonable jurists have disagreed, a disagreement caused by ambiguities in how the applicable statute defines the term "machinegun."
An Act of Congress could clear up the ambiguities, but so far Congress has failed to act. The Bureau of Alcohol, Tobacco, Firearms and Explosives (the ATF) has been on both sides of this issue, with its current regulation (the Rule) banning bump stocks as a machinegun part. In this situation, the rule of lenity that is applicable to criminal offenses requires us to rule in favor of Hardin.
