Need Help with Savage 2400.

Have a Savage 2400 12ga over .308 made by Valmet that the rib has come unsoldered on on the back section. Rib is a 2 piece affair with one piece being short and runs from the rear sight to the rear of the barrel. Rib is drilled and tapped and had a scope mounted on it. Was it originally drilled and tapped by the factory? Will silver solder hold the weight of a scope under recoil of a 12ga or .308? The way the rib is made in that area makes me beleive it may have been factory drilled and tapped for a scope mount as it starts wide at the rear of barrel then thins down then widens again for a ways at the rear sight. Anyone familiar with this model that can answer my questions? Thanks.