Originally Posted by D.Camilleri
I have recently been seeing a change in point of impact on my 338 rum after bouncing around on the handle bar rack on my ATV. I have a Sightron S-III 8-32-56 with burris tactical rings and an egw heavy duty 20 moa picatinny rail. After bouncing around on some rough two tracks antelope hunting, my POI moved up 3 inches and right 7 inches at 100 yards. I found this out after two bad hits on antelope. When I got home, I removed the scope and checked my base mounting screws, all tight. I remounted the scope, went back to the range and resighted my gun. I had to move the scope down 3 MOA and Left 7 MOA. When I was done, it grouped perfect.
My big question is: Should I trade out my 20 MOA base for a 0 MOA Base so that the scope adjustment will be more centered in the tube? Currently I only have about 6 MOA of down travel in my up down adjustment. The S-III has 100 MOA of adjustment, so I really don't need the 20 MOA base to get to my max distance of around 1300 yards. Could having the adjustment be so close to bottoming out comprimise the integrity of the adjustments? The tracking of this scope has been very good, but I went out to the range to double check the zero and I found that I was shooting 3 inches high again. This was after bouncing around on the ATV again and would explain why I over shot a muley a couple weeks ago.
In my opinion 20 moa bases are to much for the distance you intend to shoot. a 5 MOA or at most
a 10 MOA should keep you close to center of the adjustments,
When you get to the extreme limit of the retical adjustments problems are common.
I like to site the rifle in at 100 or 200 yards, look at the ballistic table for your load and then, using the drop chart look at the elevation required to hit center target at 1000 yards (Or your target distance) and add a MOA base with the same (Or close) MOA . This will help keep the scope close to center.
This should keep you within the scopes range of adjustments.
This may solve your problem.
J E CUSTOM