I use them on my scout rifle so I can access the iron sights if I need to.
They are also a good option if you have two scopes for one rifle, kind of the opposite of what you are doing.
I have never tested them but I've never noticed a problem either. Unfortunately when I miss its usually my fault as much as I would like to blame the rifle
I think the real question is how much do modern "standard" rings lose zero? Like you say aside from the QD function what's the difference really?
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