Maine's deadly mass shooting has inspired America's latest run on guns

Two days after police say a 40-year-old firearms instructor killed 18 people and wounded more than a dozen others at two separate businesses in Lewiston, Maine, President Joe Biden asked at a campaign fundraiser: “Who the hell needs an assault weapon that can hold, in some cases, up to 100 rounds?” As the president was calling out the easy access to such weapons, daily sales at a Maine gun store were some 500% over expectations, its owner said.

Who could have predicted that the horrific mass shootings in Maine carried...