Need Help sighting in Umarex Origin with Nikon Monarch

This is a new gun and first time sighting it in. Groups at ten yards started out several inches low. I continued to adjust the scope up til it hit the limit on the adjustment, and it is still about an inch low. Wondering if it is the gun or the mounting of the scope, the scope was removed from another rifle intact with the mounts and everything mounted clean. Not sure where to go from here.