I have a similar issue to the previous FSB question.  I too am new to TBlackG and had a mis aligned fsb.  I have four hex screws that allow me to loosen this and move it left to right.  The upper is a DPMS.  Are these screws typical at all or is the sight usually welded in place?  I like that I didnt have to go to the mallot technique to straighten the FS but am afraid that it will not remain in place held by the screws.
Any feedback will be appreciated.

The normal AR front sight base installation utilizes tapered pins to secure the sight to the barrel.  The sight you refer to is probably made by Armalite.  They are the only company I know of that clamps the sight to the barrel using "Allen" screws.  The clamp arrangement works just fine and allows fully adjustability of your sight base allowing you to center your rear sight when zeroing the weapon.

The gas port hole in the barrel is about one-half the diameter of the gas port hole in the bottom of the front sight base.  This allows for some movement of the front sight base without covering the gas port.  If you start moving the front sight base around don't move it too far or you will start to cut off the free flow of gas to the action.

thanks for the info gents.  I had taken the rifle to a local gun shop and the guy there didnt have a clue.