The M1911 is a .45 caliber pistol with a 7 round magazine. It can be found in both residential and supermarket spawn locations. It's approximately two-thirds as common as a Makarov PM, but is still the second most common pistol.
In version 1.7.1, it become possible to convert .45 ACPRevolver ammo to M1911 Mag.. As a result, M1911 ammo effectively became more than twice as common.
ArmA2 1.62 drastically reduced the damage done by the M1911. Before the update, it was able to kill zombies with one shot; after, it now takes 4 body shots.