I used to do them but suffered a really bad injury doing them. I dont reccomend it since its not a natural movement and too much risk of injury exists IMO. I was doing the movemnet correctly and wasnt cheating etc. I was using a straight barbell, the long full size 45 lb kind.
Something happend on the dorsal side of my forearm which caused damage to a branch of my radial nerve. I couldnt hardly pick up a bar without intense pain. It took forever to heal too. I think it was close to 1 year before I was painfree.
This movement is a bad one IMO and should be avoided.