A scope on a carry handle is going to be 4" or so over the bore.
Try to get it sighted in at 50 or 75 yards. It's going to hit low at closer ranges. Nothing you can do about that.
I just noticed what he was trying to do and am in full agreement. It would take a miracle if he was able to get that set-up zero'd at 25 yards.
Using some basic information I calculated a 2" MPBR (maximum point blank range).
- approx. 2/3" low at 25 yards
- first zero approx. 32 yards
- second zero approx. 82 yards
- 2" MPBR approx. 92 yards.
Still doesn't get him down to the 3rd mildot so I'd recheck everything and swap the rings around.