So I recently mounted a scope on a rimfire pistol that uses 3/8" dovetail tip-off mount. I purchased the high-quality Leupold Rimfire 3/8" rings to use. Paid a little extra, but figure they would be high quality items.

When I mounted them up, I noticed that the scope is slightly off-center. If I mount the rings with the clamping-screw on the same side, they line up. But if I mount the rings with the clamping screw on opposite sides, the rings are offset by about 1/16". This means that when I put them both lined up properly, my scope would be in theory offset from the center-line of the barrel by about 1/32".

Now, in theory, if I zero at 25 yards, it should be okay. But if I shoot out to 50 yards, I will have to worry about elevation (obviously), and also a side-to-side shift.

Is this really an issue? Or am I way over-thinking this?

Thanks!

as long as it is straight in relation to the bore you should have no problem.

I would definitely have them with both mounting screws on the same side.  If you have them on opposite sides then you are going to tweak the scope tube, rings, the base or all of them depending on which is stronger.  Obviously they are not symmetrical and they probably should be.   I'm not sure if there is a reason you want to have them on opposite sides for clearance of something or aesthetics.

The bore axis and the scope tube axis optimally should be parallel to each other.  If the scope is offset and you zero it, in order to maintain a zero at all ranges the offset of the scope should equal the POI at all ranges.  For example if your scope is offset from the bore 1" to the left, your point of impact of the bullet on the target should be 1" to the left of the bulls eye at say 25 yards.  If you zero your scope to be on the bulls eye at 100 yards, the further out you shoot your point of impact is going to move to the right and in theory may be 4" to the right at 400 yards.

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1/32" is no big deal at all.  Especially on a pistol.  With centerfire rifles that have more of an offset like 1/2" (think scoped Garand or scoped Enfield), you can zero with constant offset, so that your zero does not move horizontally as you shoot at extended ranges.  1/32" is way less than the adjustment on any scope, so this really doesn't apply to you.

This is what I was thinking. 1/32" would not be much to worry about. I think I was over-reacting.

And no, I would not mount them with the mounting screws on opposite sides. That was only done to see if the rings were going to be exactly centered over the barrel.

I will probably zero the scope at 25 yards, and mostly shoot at that range. When I do stretch to 50 yards, the left-to-right offset will probably not be noticeable. I don't think I will be trying out to 100 yards, though that would be fun to try at some point.

Thanks guys!