"It starts to become a safety factor," said Shane Schapiro, the union's president. He said officers are overworked and unable to take time off. "Officers were told that they could be there up to a year doing all this gun paperwork that the state police is so behind on."

Maryland State Police consult 16 databases to complete a gun background check, a standard tougher than federal law. While Maryland prohibits people without a collector's license from purchasing more than one gun per month, there is not a prohibition on applying to buy more than that, said Shipley, the state police spokesman.

About 420,500 people own regulated firearms in Maryland, according to the state's last count in March, Shipley said.

John "Travis" Kijowski of Hagerstown picked up two additional handguns since state lawmakers started discussing tougher gun laws earlier this year. He said he finds it unfair to give police his fingerprints when gun ownership is enshrined in the U.S. Constitution and he's never done anything to suggest he's an irresponsible gun owner.

"If people were asked to give fingerprints to vote, imagine the outrage," Kijowski said. "We're not a bunch of nuts. We're regular people — people who just want to be left alone."

Advocates of the new law — which also aims to keep guns away from people deemed dangerously mentally ill — dismissed the hustle to buy guns.

Vincent DeMarco, president of Marylanders to Prevent Gun Violence, said the licensing provision is designed to deter so-called straw purchasers from buying a gun on behalf of someone who isn't allowed to own it. Other states with such laws, such as New Jersey, have lower rates of gun deaths.

"October 1 is almost here, and Maryland will be a much safer place," DeMarco said. "The guns that are a problem are the ones that they buy for criminals. All we can do as a society is to enact the most effective tools to prevent gun violence, and that's what we've done."

Baltimore Sun reporters Kevin Rector and Luke Broadwater contributed to this article.