11mm or 3/8 dovetail and ring height vs. Objective

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dwostler
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11mm or 3/8 dovetail and ring height vs. Objective

Post by dwostler »

Say I have a Mauser 107 22 lr rifle and I want to put a scope with a 44mm AO objective, what height should I get and I would assume it is a 11mm dovetail. How can I be sure? How do you measure the dovetail to see which one, is it as simple as breaking out the calipers and measuring 0.433" (11mm) or measuring 0.375"(3/8)?

Thanks, Dennis
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Re: 11mm or 3/8 dovetail and ring height vs. Objective

Post by pdeal »

Dennis:

I saw your post in the Marketplace about this too but thought it might make sense to answer here since it's sort-of a general question that might be useful for others. This is really two questions in one.

1. How do you measure a dovetail on a rifle? Dovetails lock up by two surfaces mating on each side. Because of this measuring the tips to determine what you have is not reliable. It is useful in some cases though. For example the cz 452 Americans have 3/8" dovetails and other cz 452,455, 457's have 11mm dovetails. If you want to compare one cz to another to see what it has (3/8" or 11mm).

I put an image below to show how dovetails can be measured precisely. You need two pins. For 11mm dovetails I use 1.5mm dowel pins. They are cheap (about $10 for 50) and precise (usually within +/- .0001" dia. This is the best way to measure a dovetail. So if you get some 1.5mm dowel pins you can lay them in the dovetail grooves and measure to the outside edges of them with some good calipers. The measurements for a few guns that I have come out as follows:

Anschutz 11mm dovetail - .534" (54.18 action, 1.5mm dowel pin)
CZ 11mm dovetail - .525" (cz 452 silhouette, 1.5mm dowel pin)
CZ 38" dovetail - .553" (cz 452 american, 1.5mm dowel pin)

My 11mm rings fit the anschutz and cz 11mm dovetails, my 3/8" rings fit the cz 452 american dovetails well.

The other difference is that 11mm dovtails a 60 degrees and 3/8" dovetails are 45 degree.

2. How to figure out how high the rings ought to be? I have had some guys make a little carboard cutout to check the height of the scope off the barrel. Also, I have had many people call me for odd scope/rifle combos and I do some measuring to figure out what ought to fit based on the objective diameter of the scope. Generally though for mine the .7" high rings work pretty well with a 44mm obj. Unless there is a rear sight on the barrel that might interfere with the objective.

dovetail.png

This image came from the following link: https://www.engineersedge.com/mechanica ... _14212.htm

McMaster Carr would be a good source for a life time supply of dowel pins for measuring scope dovetails incase anyone is intereste:
https://www.mcmaster.com/dowel-pins/sys ... ter~1-5mm/
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Last edited by pdeal on Sun Jan 17, 2021 9:55 am, edited 2 times in total.
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dwostler
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Re: 11mm or 3/8 dovetail and ring height vs. Objective

Post by dwostler »

Thank you, this is very helpful!

Dennis
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