The 1903 banded sight base is held in place by the cross-pin.  If you remove the pin, the base can be driven forward off the barrel.  There may be a loose spline that holds the base from turning and locks it in place.  The spline is held in place by the cross pin.

I would suggest you remove the rear sling-swivel from the stock and plug the screw holes.  If you remove the front swivel from the Rifle barrel-band, the band can be more tightly clamped in its proper place on the stock.  (Another option is to build up the stock, where the band seats, with glass-bedding).  The hand-guard plays no role in tensioning the barrel band.

(photo shows forearm 'shoulder' that keeps barrel-band in position against band-spring).

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