OLD AND WRONG: Just did the math for that ANSI test, and the steel ball should impart a bit under 1.6 joules on the glasses. I used the mass of a 1 inch wide cube
of steel though so the energy would be a bit higher than what it actually is. This was assuming the steel was 7.9g/cm^3 and solid. So the energy wasn't much more than a 0.2g BB traveling at around 416ft/s. My math could be way off though.
If I got it right however, I think looking towards a tougher ANSI projectile resistance standard would be advisable.
EDIT: Little late, but just redid the equation on paper today and found out that Google did a really wonky conversion and gave me way too high of a density. I got the same 0.6 joules reported after this post.