Spent all yesterday afternoon mounting and sighting in the neighbors Rem. 770 .308. Replaced the Package scope that went out in 4 shots with a Centerpoint 4X16. They come with their own rings. Bore sighting and shots from 25 yds maxed out the elevation and left it at 14" low. This will equate to around 10" at 100 yards. So obvious solution is to shim the scope. 2 possible fixes are: Shim the base (rear) Shim the ring (rear) Personnaly I perfer to shim the ring first. The scope on my Rem 700 is shimmed on the rear ring and has been for about 7 years and still holds sub .5" groups with hunting loads. I use aluminum cans, take your pick, Beer (any brand will do), Soda, I used Mountain Dew as it was the first one I picked out of the recycle barrel. I cut the top and bottom off with avaition shears using the side metal. I washed the metal and sprayed it down with brake cleaner and wiped good. I then cut strips to match the ring width and length to go UNDER THE SCOPE, BUT NOT ON THE SIDES. For this application I used 2 strips. On remounting the scope, bore sighting and re-firing at the 25 HAD PLENTY OF ELEVATION. Moved back to the 75 and had to COME DOWN ABOUT 32 CLICKS to get it centered. Worked great.....again. Note: If your prefer to shim the base, which I have, May I suggest to use a piece of Old Measuring Tape. The contour is just about right to fit the curvature of the barrel, and even is the mounting surface is flat it will flatten out fine. Just drill holes. Only problem with base shims is SOMETIMES the screws with the origional base will not be long enough and you will have to obtain new ones.