the plastic case is safe, the glass i'm not so sure, i expect it will crack, but not shatter. There is a video of one being thrown out of a plane and being perfectly serviceable afterwards.
I used my sniper rifle which fires 430fps with .2s. It took several shots of .36 at point blank with no marking on the glass at all, no chips scratches or cracks.
I shot the case several times and the paint started to flake but the plastic remained intact. I may charge the go pro and do a video tomorrow including unloading a full mag onto it.