*What is a Glock switch? Putting a Glock switch on a gun is illegal. But possessing a Glock switch is also illegal in and of itself. Someone caught with a Glock switch can face up to 10 years in prison if prosecuted at the federal level. The penalty can vary widely though, various cases show.* *A Glock switch functions by applying force to a semi-automatic pistol's trigger bar to prevent it from limiting fire to one round of ammunition per trigger pull. It thus converts the weapon into a machine pistol capable of automatic fire.*