Aimpoint H-1 on Glock 17 - How to Zero the sight?

[phkk]

One of my friend just bought an H-1 Aimpoint for his Glock 17. It seem he can't calibrate the sight for his Glock, the shot went down like 5-8inches from the target.

The top adjustment already turned to the max ( can't turn any more).

Does any one know how too?

Target at 25yard

[badicedog]

Tell him to sell me his H1 and get either 10-8 or warren sights!