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1 had a too-loose turning base and had to be returned.
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I have run into that before with this exact setup. I just tighten them back up buy putting the ring over a pefect sized socket clamped in my vise for support and then tap on the ends of the dovetail to slightly bend them closer to the ring if you will. It usually takes very little to tighten them up and the change is undetectable to the eye so you have to trial fit them often to avoid over doing it. I like them to need a 12" extension in my socket to turn them in with lots of Never Sieze on them. I do this all the time on older dovetails that are worn from being turned to much or without proper lube on them.
Leupold recommends the double dovetail configuration on hard kicking applications like magnum revolvers and heavy scopes on lightweight rifles. The only reason I can think of for pushing the Mark 4 stuff is the base has a 1/4 minutes slope built into it and for a true combat tacticle rig they are a little stronger. The weak link is always going to be the puny screws that hold the bases on.
I really like the Leupold bases with the Burris Signature rings in them. The new 30mm rings have 4 torx srews holding the caps on. They are a very solid setup.