.22 and .38 Super (think of it as 9mm Magnum, almost like .357 Mag. without a rim) are the most common calibers of arms in Mexican civilian hands.
The .38 Super is used in a variation of the Colt 1911 pistol.
I've also seen the .38 Super in a Taurus and European Sig 220. Smith also made a moonclip revolver chambered for it in small quanitities. The 1911 variation is most common as you said.
***The .38 Super is used in a variation of the Colt 1911 pistol.***
In Mexico, the .45 ACP is a military round and not legal for civilians. As a result, the .38 Super rules!