I just mounted a Nikon Prostaff 3x9x40 on my flat rear 7mm rem mag using DNZ Game Reaper one piece mount. I contacted the manufacturer about fitment before ordering the part. They said it should fit. The base lined up and installed perfectly. I dropped the scope in and the adjustment ring was barely hitting the rear base. I filed about 1/16" off the area it was touching and it gave plenty of clearance. The base is pretty meaty in this area so I wasn't overly concerned. I bore sighted the scope and had it close at 50 yards within 3 shots. There is plenty of room to cycle the bolt and load the rifle. I was impressed with the quality of the machining and the ease of installation. I really wanted to use the low mounts to keep the scope as close to the rifle as possible.
I thought I would share my experience with anyone interested.