Magazine Safety

[¦mag·ə¦zēn ′sāf·tē]

Also called a "magazine disconnector." A device that prevents a pistol from being discharged when the magazine is removed. A mechanism for an automatic pistol, to make firing impossible unless the weapon contains the magazine.  A magazine disconnect is an internal mechanism that engages a mechanical safety such as a block or trigger disconnect when the firearm's magazine is removed  (Warning: These devices are not always reliable.)

Magazine disconnect
Magazine disconnect