CodyM:  Although not an '03 or '03-A3 sight base, this banded front sight was installed on a Krag Sporter, that I have, in a similar fashion used with the '03 & '03-A3 sights.  (I believe my Krag has a recycled Model 30 Remington sight).  Please note the Krag barrel appears to 'step-down' and there is a second pin, almost invisible, holding the banded sight in place.

---