I'm looking at putting a red dot on a handgun and I hear reviewers talking about it being a pain to re-zero anytime you take the optic off to change batteries or whatever. My question is, how far is it generally off when you put it back on? I mean, they usually mount on a flat plate with screws and pins bringing it back pretty darn close to where it was, right? I can see some slop being possible if there's some adapter involved but otherwise I wouldn't think the pins and screws would give you much leeway to mess it up. Please set me straight