New to the forum. I got tired of searching the internet for this answer and figured I would give this a try. I am confused on which exact scope base I need. I have tried researching this, but just keep going in circles. Let me try to explain the problem and hopefully it will help clarify the issue. I use a Larue Tactical quick detach scope mount on two of my rifles. This allows me to purchase one scope and switch it back and forth between rifles very easily without losing my zero. The two rifles I use the QD mount on is the DPMS LR308 and the Savage 111 in 338 Lapua. The only downside to this method is that you have to adjust the tightness of the QD levers if the thickness of the picatinny cross slots on one base differs much from the other. But if the thickness of the cross slots are the same on both of your picatinny rails, switching out optics is a breeze and no adjustment is necessary. Since I cant really replace the flat top rail on the DPMS, I have to match it with the base I install on the Savage 111. On the Savage 111, I currently use an EGW HD Savage Round Back Long Action Picatinny Rail Scope Mount with custom drill #8's screw holes. However, the thickness of its cross slots does not match the DPMS and requires me to adjust the levers each time I change optics. I measured the thickness of the DPMS and Savage cross slots and they are: DPMS Rail Slot thickness: .196" EGW HD Rail Slot thickness: .185" Am I even measuring the right thing here? How on earth do I go about finding a base that matches the DPMS?