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Old 03-04-2017, 07:39 PM
redlightrich

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Scope ring mounting distance



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Hello all, scope newb here again. I followed the advice of this site, and purchased Burris Signature rings for my new CZ 455.

One person recommended to set the rings 3.6 inches apart ( which made sense to me being 100 yards = 3600 inches, so the math to shift it would be easy.

My question is should I set the rings 3.6 inches apart from outer ends? Or 3.6 inches apart center to center. Keep in mind, the signature rings have an insert which appears to be plastic or nylon or something like that. They make them in offset sizes to correct any problems that the scope itself may not handle.
I am not sure if that info factors into the answer.

Please be patient with me. I did search here, and the web, and I am not finding the answer. I am new to optics, and there is so much I have to learn!!!

Thank you for your help!!

Rich
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Old 03-04-2017, 08:11 PM
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Methinks the vert has been dialed up while thy back hast been turned.

Going hunting for snipe later tonight. Bring that big croaker sack--you're gonna need it.

Are you talking 3.6" on the dovetail or the tube?

"They make them in offset sizes to correct any problems that the scope itself may not handle."

I'm right there with your^^.

What size rings do you have? What kind and size--tube diameter--is your scope? What are you thinking about eye relief?
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Old 03-04-2017, 08:26 PM
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i have always done it at 3.5 inches apart center to center, that's what i was told years ago.
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Old 03-05-2017, 08:28 AM
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Hopefully the scope base is uniform. I set my rings as far apart as the bases allow.

Scope ring spacing has nothing to do with the adjustments the scope has nor anything other than just holding the scope solidly.
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Old 03-05-2017, 09:52 AM
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The scope rings are for a 1" tube. I didn't test fit yet, so I don't know the eye relief measurement.

I am as green as you can be with this. I have always used iron sights. Yes I have used a scope, but I placed no thought into it. On a 10/22 that I have, I put a cheap scope on, made a few clicks, and it was more accurate than me.
I am attempting to try my hand at hitting tiny targets with a bolt rifle.

I bought the Burris Signature rings, based on a recommendation from a member here, then I researched them, and heard good things.

I agree, that unless something is very wrong, I should not need to use the eccentric ring inserts. However, if for some reason I had to, the calculation may be easier with a specific distance apart on the mounts.

Some fellow posted up a math calculation that "proved out" 3.6 inches apart on the rings were optimal.

Maybe, the reason I can't find any info on this is because it is not an often used practice?

At any rate, I still didn't pick out a scope, but I am now committed to a 1" body.

I went to look at scopes yesterday, and became more confused than ever. I tried a higher power nikon and a less expensive 3-9x40 and at all distances the cheaper scope appeared clearer to me after I adjusted it. The sales person said that the higher magnification can show less clarity on the lower price models. He said if you want higher power, and equal clarity, then you may want to buy a more expensive scope. This store did not sell any scopes that were over 300 dollars, so he was unable to demonstrate, but based on the Nikon and cheap BSA comparison it made sense.

Based on my current level of confusion on this, I think the best move for me is to go to my gun club, and ask the shooters on the 100 and 300 yard ranges to let me peek thru their scopes. Most people are friendly and more than happy to share their experiences. Even though this is for my 22, and I probably won't stretch it out past 100 yards, the perspective will be helpful on the 300 range. It will also be helpful if I scope my higher power rifles.

I am not sure why I didn't try this approach first.

Thank you all for your thoughts

Rich
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Old 03-05-2017, 10:00 AM
NoSecondBest
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Quote:
Originally Posted by Travelor View Post
Hopefully the scope base is uniform. I set my rings as far apart as the bases allow.

Scope ring spacing has nothing to do with the adjustments the scope has nor anything other than just holding the scope solidly.
This is correct. There is no "correct" distance to set the rings apart. I have no idea who started this myth, but there is no truth to it. Calculating POI based on bbl. length, sight height, etc. is formulated and places like Brownell's has that info posted...but it's for open sights, not scopes.
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Old 03-07-2017, 01:30 PM
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Quote:
Originally Posted by Travelor View Post
Hopefully the scope base is uniform. I set my rings as far apart as the bases allow.

Scope ring spacing has nothing to do with the adjustments the scope has nor anything other than just holding the scope solidly.
DING, DING, DING......we have a WINNER. This is the correct answer.
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Old 03-07-2017, 02:18 PM
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http://www.burrisoptics.com/sites/de...nstruction.pdf

Note ring spacing chart.

I have 3 sets, and I never found spacing to matter. You still have the scope adjustment. ( the rings just have get you close enough to use it. )
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Old 03-07-2017, 04:21 PM
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Place the rings as far apart as possible, to reduce the "leverage effect" against the rings.

I mounted an old El Paso Weaver K10 on a Savage .17HMR last night using Burris Sig. rings and a picatinny rail. As usual, first I mounted the rear ring as far back as the rail will allow. Then I set the scope in the rings loose and got the eye-relief perfect. Then I mounted the front ring as far forward as the rail and the objective bell allow.

Can't wait to shoot it!
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Old 03-07-2017, 05:08 PM
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I also space the rings as far as the rail, scope, and eye relief allows. Yes, different spacing than 3.6" will change the value of the burris shims slightly, but it's not a lot.
A closer spacing will increase the value a little and a larger spacing will decrease it.

As you already know, there's 3600 inches in 100 yards.

Just divide the distance to target by your ring spacing and multiply that by the value of the shim which is supposedly in thousandths, if I recall. The math is not at all that much harder... especially with my calculator.

Example... if your ring spacing is 4" and your total front and rear shim value is +25 it would be:

(3600 / 4) * .025 = 22.5" and this is roughly how many inches your impact would be raised at 100 yards.

This formula works with iron sights as well if you're trying to figure out how much higher or lower you need the front or rear sight... impact change needed divided by distance to target multiplied by you sight spacing.

As it's been said, it will have no bearing on the value of your scope adjustments... it will just get your scope closer to where you want to be without using as much of your scope's adjustments. One of my scopes has 80 moa total (40 in any direction) which more than enough to get to 200 yards with sv ammo from my 50 yard zero, but I still use +20 to get it closer so it's not so far from optical zero from one extreme to the other... however this is probably only important to rifle loonies.

Hope this helps.
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Last edited by JEE; 03-07-2017 at 05:16 PM.
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Old 03-08-2017, 07:56 AM
Lloyd S.
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The advantage to 3.6" spacing C-C on Burris Sig rings is that that's the spacing that makes the elevation change in MOA equal to the markings on the shims in thousandths of inches. Otherwise, makes no difference.
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Old 03-08-2017, 11:43 AM
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Okay, but that seems like a silly thing to be trying to factor in. Half the time I end up rotating the inserts so that TDC is at the 10:30 position, or the 2:15 position, etc., anyway, so I don't know exactly how many MoA's of correction I am applying vertical and horizontal even if I would know exactly if TDC were at 12:00.

I mount the scope, shoot the berm at 25 yards and see where I am, then use my best guess at which inserts oriented which way(s) will get me the closest. Then I move to 50 yards and repeat until I have it as close as I can get it, then use the turrets to finish up. Doesn't take that long!
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