Not surprised - it would take a lot more than gunshots to break a mirror. In Sydney the windscreens on the recent train fleets are made to withstand a concrete block at 140km/h, using multiple layers of glass bonded together. The outer one will break but the driver behind is safe.
It's tough alright. Maybe the shooter was trying a new way of 'hands-free' collimation? Or testing as to whether a bullet would bounce off the primary, onto the seconday and down through the eyepiece...
