High-angle heavy guns and ammunition weight

How useful would a battleship's very large high-angle main-gun battery and magazine be?

The ammunition would be valuable, but turret, magazine, elevation, and hull-stress constraints make the arrangement extremely demanding.

A large capital-ship gun is considered high-angle well below vertical elevation, and hull stress limits extreme elevation. The normal stock of roughly 250 shells per main gun also shows how quickly magazine weight dominates a design. Eight 15-inch guns with that allowance imply about 2,000 heavy shells before propellant and handling machinery are counted. Greater elevation can extend range, but turret weight, recoil, and hull strength prevent the battery from being judged by gun count alone.