Ok, here's another idea. Get youself down to Supercheap auto and buy a 9/16 single hex socket that is non impact(just a standard Cr vanadium type). Use that on the rattle gun but wear some eye protection and gloves incase the socket disintegates. The standard sockets dont have such a deep radius carved out on the underside and should hence sit deeper around the bolt. Also the thinner wall will also enable it to get down deeper.
I've been using a standard cr-van socket for a couple of years now and it hasn't failed me yet. The problem with the cheaper impact guns(like the set i own)that come with a set of sockets is that they're metric and are always a nuisance trying to get off 9/16 bolts with the slightly smaller 14mm soccket that's supplied.
