COLUMBUS, Ohio (WCMH) — They are small, illegal and they make weapons more dangerous — and police said they are finding them in Columbus.

The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) calls them machine gun conversion devices. They are often also called Glock “switches,” although Glock does not make them. 

“The danger comes in the fact that they convert a semi-automatic firearm to a fully automatic firearm, or essentially a machine gun,” said Sgt. James Morrow, a sergeant in the gun crimes unit with the Columbus Division of Police.

The switches are about the size of a highlighter. Morrow said criminals are attaching them to Glock handguns. 

“They depress mechanisms inside the firearm that allow the slide to continue to action and the gun to continue firing as long as the trigger is depressed and as long as there is ammunition in the firearm,” he said. 

One of the ways the switches are being made is by using 3D printers, Morrow said.

Officers were serving a search warrant earlier this week when they found four guns, he said, and one had a switch on it.

“We’ve obtained more of these machine gun conversion devices this year than we did all of last year,” Morrow said. “Already this year, we’ve obtained 22 of them through our investigations, and I expect that number to continue to rise.”

The devices are an issue in the Cincinnati area, too.

Both the ATF and U.S. Attorney for the Southern District of Ohio have discussed the dangers of them. The ATF also put on a demonstration firing a weapon without and with a switch attached.

Getting the devices off the street is a priority for Morrow’s unit, he said.

“We’re currently working with some patrol officers that have noticed these on the street or noticed them through their investigative means,” he said. “We’re going to continue to work with those officers to attack this problem and take as many of these off the street as we can because if we can prevent one shooting, it’s all worth it.”