I recently put together an AR using an upper from J&T.  I haven't had a chance to shoot it yet, but while running an oiled patch through I found that it gets caught slightly.  I checked to see about where this happens and it is at the gas port.  Is this anything I need to worry about?  Is it normal?  Will the proble disappear after a few rounds have been fired through it?  Thanks for any help.

This is common. Unless there is a great big stalactite like burr hanging down, don't sweat it. It will smooth up after a few rounds. If it bothers you, work the area with a tight bronze brush and some J&B Bore Paste.