Rifle Scopes Ring Height Info - How to Measure Correctly

[Archer01]

I sent a post to affirm MY retirement, however a complete complex screening of new "service toys/with accessories" have been pressure tested in diverse field environments and index.

 

[JOEREZ]

Re: Ring Height Questions

The above is taking into account the butler creek caps. The ones i have are aprox .035-.040 thick and get thinner when stretched over the scope. I have been known to sand down butler creek caps to allow the use of lowest possible rings...

Clearance is just that, it doesn't matter if you have 1/16 inch or a foot, its still clearance. On a .50 cal it might matter...

Why might it matter on a .50 cal?

 

[Big5]

Guys,

Lately, on average of about 1 per day, I have seen quite a few posts (mostly from newbies) regarding questions about what ring height should be used. They usually request pics for comparison. For all new guys, there is a systematic way of calculating ring height that doesn't require more than a simple elementary school ruler. You measure 3 things:
1. the height of the front of your base/rail from the barrel
2. the height of your rings from the top of the rail to centerline
3. the outside diameter of the bell of the scope (not the size of the objective lens)

Here is the equation:

[rail height + ring height] - [bell diameter x 0.5]

If the value is positive, then your bell will clear the barrel. Ideally, you want that bell to be about 1/4" or less over the barrel. This will give you a tight cheek weld. Be sure to account for Butler Creek caps if you intend on using them.

If you are using a 40mm objective, then you can use the lowest rings and bases available, as the bell will certainly clear the barrel with no problem. i.e. don't worry if the bell ends up being higher than 1/4" over the barrel.

Hope this helps.

mike

Just another note. If you are using a scope base and/or mount/rings that have built in elevation, that may have to be accounted for in the case of very small clearance. To calculate this, we need to know the amount of elevation built into the mount/rings and/ or base, and the length from the end of the scope base to the end of the scope bell. Convert MOA into degrees, and then the equation is:

Tan ? x length

For example, if you are using a 20 MOA base, and the distance from the edge of the scope base to the end of the bell is 5". 20 MOA = 0.333 degrees, so:

Tan 0.333 x 5 = 0.029"

This means that you need an extra 0.029" of clearance in addition to the calculation above

-mp

Thank you for the information!

 

[mikethetiger55]

I am looking for some help, and yes, I saw the calculator I am in the process of putting together the final pieces of my rifle and I am trying to place an order for scope rings, but I'm struggling with the height requirement. Rifle is a R700 with a Bartlein 3B barrel and I am adding a 20MOA Area 419 Rail, which I don't have yet. My scope is a Nightforce SHV with a 50MM objective (should be 59MM OD) which I would like to put in ARC M-Brace rings.

I can account for the scope (29.5MM) + I am using 2MM for cap thickness so that puts me at 31.5MM or 1.24 inches. I don't know the rail thickness as I don't have it yet, but it looks like I am at the high ring mark (excluding barrel taper & 20 MOA rail). This feels off based upon what others are saying but I know the math is right, obviously excluding a few key factors. I am trying to have everything ordered together.

Anyone with a similar setup or insight?

 

[gasrat]

I didn’t go through every page. But if it’s not been posted, this may be of help to someone.

 

[spentbrass1]

When measuring the distance between the center of the rifle bore and the center of the scope do you measure from the back of the scope the center or front to get your distance

 

[Rob01]

When measuring the distance between the center of the rifle bore and the center of the scope do you measure from the back of the scope the center or front to get your distance

Windage knob to get height above bore for ballistic program.

 

[spentbrass1]

Windage knob to get height above bore for ballistic program.

View attachment 7862279

Thanks

 

[BobV]

Re: Ring Height Questions

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fritz24</div><div class="ubbcode-body">I have no problems with bell/barrel clearance - but as we speak am having a mounting issue where the scope's bell is making contact with the forward end of the 20MOA base(a Seekins base as it happens). I can't get the scope back far enough for proper relief without contact with low or medium rings on my 700P. (Scope is 10x40 SS)

Is it just me? </div></div>

I personally havent heard of this problem. It may come down to you needing a different mount. Maybe Glen or someone will chime in with a solution.

I had to trim one picatinny lug’s worth of rail in order to mount 50 and even 44mm bells far enough back for proper eye relief. Thankful that i had Brownells Alumablack and Ampho Blue on hand.

 

[jonny5isalive]

Helpful! Thanks for sharing.