I've seen it happen with Rockets Rock. I think they were the "steel head". I goofed and hit dead center shoulder right at the spot where most aim with a firearm. Arrow came back almost as fast as it went out! Now granted, from a 150# x-bow it sure shouldn't happen but it can and obviously does. I typically see penetration from them but with heavy bone hit, blades break off and it's just the ferrule and arrow going through.