That's something I haven't seen before - bottom of the notch for 50 zero, level with the wings for 150, then 200 and 250 leaves.

I found with my .69 and round balls, that bottom of the notch gave 100 and top of wings gave 200, so 1/2 way is roughly 1/2 way. Handy to know for hunting.

The 200yard leaf appears it would work the same way, top of wings would give 250yards zero, and I'd lay odds the top of the 250 yard leaf's wings should be very close to 300 with the bullets.