50 BMG was not developed to shoot people, it was developed in 1920 to shoot the then-new tanks, and during the past 90 years it has done many tasks well (including shooting tanks). IIRC, a 50 BMG will shoot through 6" of armor plate or 13" of reinforced concrete.
Here i have a link that a .50 bmg AP can penetrate 25.4mm of RHA at 200 meters.
here is a other link
As far as i know global security is pretty reliable.