Loc tite is necessary on the buffer tube castle nut if your not going to stake it. It's also necessary on back up iron sight screws.
As said above, NO NOT use it on the barrel nut.
If you have a low profile gas block, send the barrel/gas block to ADCO and get it pinned. Even with set screws it can and will move making your rifle useless.
Last edited by Cole125; 10-11-2012 at 20:15..