[@Aeolian] Violet's shield in Incredibles was, as Junk's video demonstrates, powerful enough to stop a multi-ton robit. 

So it's basically strong enough to be immune to everything the cast can throw at it. Stopping a speeding car is fucking strong as a car is a lot of speed and weight flying at you. 

Personally I think while surviving an onslaught of bullets would be fine, a 50. cal should shatter it no question. I think it should be impervious to conventional damage ala a punch from a professional heavyweight boxer and pistols, but weak against the superhuman such as Henry should be able to destroy it after a few blows.