  How well do firearm markets comply with firearm restrictions? The
Massachusetts Attorney General issued an Enforcement Notice in 2016 to announce
a new interpretation of the key phrase "copies and duplicates" in the state's
assault weapons ban. The Enforcement Notice increased assault rifle sales by
1,349 (+560%) within five days, followed by a reduction of 211 (-58%) over the
next three weeks. Assault rifle sales were 64-66% lower in 2017 than in
comparable earlier periods, suggesting that the Enforcement Notice reduced
assault weapon sales but also that many banned weapons continued to be sold.
