How fat is a "30mm" scope tube?

[Brians356]

I've never knowingly purchased a 30mm scope. But I do own a cheap red-dot sight, probably made in China, which is mounted on an air rifle. Its tube measures 1.175" (29.85 mm). Is that the typical diameter of a nominally 30mm tube?
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[dmoran]

Yes .... 30mm/1.181" plus/minus a little

 

[Brians356]

Yes .... 30mm/1.181" plus/minus a little

So these rings should work on another 30mm scope with any luck. Thanks.
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[#40Fan]

Probably will, but the rings are probably the cheapest part of the gun. No reason to use the cheapest you can find. Nothing like scratching the crap out of a scope because of cheap rings not holding very well.

 

[Bart B.]

There's a small spread in all scope tube diameters for a given size.

Same for magnification at a given power setting on the zoom adjustment and this causes a small spread in line of sight per click in windage and elevation.

Zoom scopes usually have a small reticle shift about point of aim across the adjustment range.

Tolerances in parts shape and position can add up in some direction as they're adjusted.