INDIANAPOLIS — Indy police have seen a rise in the use of machine gun conversion accessories throughout the city and are now changing the wording they use when referring to the devices.


Machinegun Conversion Devices, or MCDs, are gun accessories that convert semiautomatic pistols to fire automatically, according to the ATF.

Under the National Firearms Act, MCDs are defined as machine guns even when not installed.

The distribution and sale of these devices is illegal, ATF says, and often done over the internet. MCDs are sometimes made with 3D printing technology.

Most often referred to as a ‘Glock switch’, the ATF says MCDs are can go by a variety of names. These include:

• Switch
• “Glock Switch”
• Auto Sear
• “Glock Auto Sear”
• Lightning Link
• Swift Link
• Selector Switch
• “Glock Selector Switch”
• Chip
• Certain forced reset triggers


While the most common of the above terms is Glock switch, the Indianapolis Metropolitan Police Department said this labeling is misleading.

“Glock does not make “Glock switches” so, while they are used on Glock handguns, it can potentially be misleading to use their name when referring to the specific device,” an IMPD news release reads.

IMPD announced Monday it is now planning to refer to the accessories as Machine Gun Conversion Devices.

“This terminology covers the variety of devices that serve that purpose and it describes what the device is/does (as opposed to “switch” or “sear”),” IMPD said.

Additional info

In order to contact your local ATF officials for more information on MCDs, click here. For a list of online ATF regulations, click here.