30, I've seen about three of these, this is a first for me though, the other owners were not willing to part with the sight unless the rifle went too.
The elevation marks go to 800, with a bit of room above, maybe 900 at the most.
Elevation arm is relatively short, mainly to clear the bolt handle when laid back, the 'V' is large enough to view the standard sights, so obviously pre '30's while the "no interference with sights" rule was still in play.