 The eastern end of the new Proof Battery was designed for test firing machine guns, field and siege guns, and howitzers – larger guns like a caliber – were test fired at the west end of the battery.In the middle were mounted a variety of guns from caliber.When a gun was fired, the gun crew stood behind thick concrete walls in the niches in case the gun blew up during testing and personnel could watch from atop a observation tower behind the traverses.