My Leupold Deltapoint Pro mounted on my P226 used to loosen its attachment to the rear sight dovetail insert after one range trip. Leupold claims they never heard of it, but sent me a complete replacement mount, which did not solve the problem. Anybody else experience this? I think the problem is that the Deltapoint mounting base has a curvature to it which does not match the curve on the P226 slide. This allows the Deltapoint to move sideways until the mount finally blocks it. After trying blue Loctite without success, I tried substituting the mounting base designed for the CZ75, which had a more compatible curvature. I used a small file to enlarge the opening just enough so it would fit over the dovetail insert supplied with the Sig kit. Then reinstalled per Leupold instructions. Knock on wood, but I've been to the range 2 times, and the little guy has not loosened yet. If it works, it's a $30 solution.

I also bought the Leupold mount "kit".
I have no idea why they didn't get it right..!
The mount "bar" that goes into the slide dovetail, is loose on every dovetail that I tried using it on.

As you did, I did a mix and match to find the tightest mount fit per slide. I didn't have any problems with the base plates on the guns I put it on.

Mike