Scope Elevation Ceiling
The point at which a scope's internal elevation adjustment runs out and the shooter must hold over the reticle instead of dialing.
Every scope has a finite amount of internal travel — usually quoted in MOA or mil. Once you’ve dialed it all up, the only way to put the reticle higher than the target is to hold over: aim the bullet’s flight path with a marked stadia line instead of the crosshair.
The ceiling matters because rifles routinely outshoot the optics mounted on them. A .338 Lapua can carry to a mile, but a scope with only 25 mil of elevation on a flat base may not be able to follow it. Picatinny rails with built-in MOA (20, 30, 40) buy back some of that travel.