I mounted a Leupold 3x9 on my HK SL8-1 and tried sighting it in at the range without having it bore sighted first (lack of time). The problem is that it was shooting maybe 2-3 inches low after using all of the adjustment on the scope. I used Millet weaver style rings (medium ht.) and there is just a c-hair distance between top of rail and front end of scope. This rifle has a full length rail for optics. Any suggestions?