Based on the photographs supplied I see the following :-
Ser No 10319, Kirk & Bagnall indicate First No for yr1902 as 10326, based on this we can assume No assigned to action and fore end was very late 1901. Crown over crossed scepters on action was used in the 1896-1904 period.
Barrel flats show BP,NP & BV in a modern "Roman Times" style font, which was in use from 1904-1954, prior to this,during period action and fore end were proofed these were in a stylized cursive font.
Based on the above I would state that the barrels,by William Ford Were a later addition. The additional serial no stamped on the fore end lug were in all probability a Ford No. Had they been contracted for the original build they would have almost certainly been numbered to the action.
I hope this helps. Enjoy the gun in good health.