On the premise that you can always use a small gas station-style ATM for cover and concealment in an active shooter situation, Edwin Sarkissian grabs a surplus one for some destructive testing.
These light Hyosung-style mini-banks use a sheet metal cabinet with a reinforced interior around the cash machine portion to help deter the average crook with a pry bar from getting some ill-gotten greenbacks. These are typically UL 291-standard “business hour” listed safes. While not generally designed to stand up to firepower, Sarkissian and crew find that handgun rounds up to and including .44 Mags from a Deagle fail to penetrate both sides of the ATM, proving the cover hypothesis to a degree.
The same cannot be said for rifle rounds — especially when you graduate to .50 BMG.