I was installing my barrel and cranked down the vise. I have two mounted vise. The big one is currently covered. I figured the littler one would do the trick. I started the procedure with no trouble. I torque it to 30ft/lbs and backed off, then again to 30 ft/lbs and backed off. I then started to torque down the barrel nut. The barrel was twisting a little, so I added a little more pressure to the barrel. I then started to torque the barrel nut again and BOOM the vice broke! What the heck was that about?
I then cleaned off the other table which took three hours and finished off the barrel nut with the large vise. I still had a little problem with the barrel twisting so I used the leather strip idea, worked great. Got to 70-75 ft/lbs when the last hole in the barrel nut lined up. Job came out great.
Thanks to all at AR15.com for help.