I recently purchased a Browning B78 single shot and have mounted a B&L 6-24 scope on it using the factory supplied rings and one-piece base. When I sighted it in I could not depress the scope's elevation enough to get the point-of-impact where I wanted it. I am shooting at least 3.5" high at 100 yds and cannot lower it any more. Windage adjustment has been no problem, and the scope has performed perfectly in the past. I am using a normal 100 gr load and accuracy is very good.
Any ideas or solutions will be appreciated.

Is your scope tube bent?

Are the rings turn-in style or something else?

Are they the correct height? If other than turn=in style, perhaps they need to be swapped front for back.

George

This problem is not uncommon, and since your problem is only with the elevation and not the windage, it is easily solved. Simply remove the scope from the rings and place a few thicknesses of aluminum foil, or if you prefer, electrical tape on the inside bottom of the front mount, then replace the scope in the rings. This will correct the over-convergence of the line-of-sight of the scope with the line-of-sight of the bore.

Burris signature rings with the offset inserts will solve your problem as well.