Maybe some troubles with nomenclature here. Do not remove the front sight base/band unit from the barrel unless absolutely necessary. If what you want to do is to remove the M1903 upper band (with the bayonet lug on the bottom), do this:
1. remove the upper band screw that passes laterally thru the upper band and stock,
2. remove the front sight stud (the piece that fits in the dovetail and holds the front sight blade) by removing the small screw in the front sight base/band unit that faces towards the muzzle. Look for a small properly fitting screwdriver for this as these screws are small and are easily buggered. Again, a soaking with penetrating oil is recommended before doing this. After the screw is removed, take a punch and drive the front sight stud laterally out of the dovetail
3. remove the upper band forward off the stock and barrel. A tight one can be moved by tapping on the rear of the bayonet lug.
To remove the barreled action from the stock after the upper band has been removed do this:
1. Remove the lower band screw and sling swivel, The lower band will pass over the lower band spring in the slot in the right side of the stock,
2. remove the handguard,
3. Remove the front and rear trigger guard screws,
4. remove the trigger guard.
5. lift the barreled action out of the stock.