## Burris Signature Rings — Calculating Actual Elevation Changes

Burris Signature Rings with polymer inserts are an excellent product. The inserts allow you to clamp your scope securely without ring marks. Moreover, using the matched offset inserts you can “pre-load” your scope to add additional elevation. This helps keep the scope centered in its elevation range while shooting at long range. Additionally, with a -20 insert set in the front and a +20 insert set in the rear, you may be able to zero at very long ranges without using an angled scope base — and that can save money. (To move your point of impact upwards, you lower the *front* of the scope relative to the bore axis, while raising the *rear* of the scope.)

**Insert Elevation Values and Ring Spacing**

People are sometimes confused when they employ the Burris inserts. The inset numbers (-10, +10, -20, +20 etc.) refer to hundredths of inch shim values, rather than to MOA. And you need the correct, matched top/bottom pair of inserts to give you the marked thousandth value. Importantly, the actual amount of elevation you get with Burris inserts will depend BOTH on the insert value AND the spacing between ring centers.

Forum member Gunamonth has explained this in our Shooters’ Forum:

Burris inserts are [marked] in thousandths of an inch, not MOA. To know how many MOA you gain you also need to know the ring spacing. For example, with a -20 thou insert set in the front and a +20 thou insert set in the rear, if the ring spacing is 6″, the elevation change will be approximately +24 MOA upwards.

Here’s how we calculate that. If you have a 2 X 0.020″ “lift” over a distance of 6 inches (i.e. 0.040″ total offset at 0.5 feet) that’s equivalent to 0.080″ “lift” over 12 inches (one foot). There are 300 feet in 100 yards so we multiply 0.080″ X 300 and get 24″ for the total elevation increase at 100 yard. (Note: One inch at 100 yards isn’t exactly a MOA but it’s fairly close.)

Here’s a formula, with all units in inches:

Total Ring Offset

——————– X 3600 = Change @ 100 yards

Ring Spacing

(.020 + .020)

—————– X 3600 = 24 inches at 100 yards

6

NOTE: Using the above formula, the only time the marked insert offset will equal the actual MOA shift is when the center to center ring spacing is 3.60″. Of course, you are not required to use 3.60″ spacing, but if you have a different spacing your elevation “lift” will be more or less than the values on the inserts.

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Keep in mind too when using these inserts that you need to put a + opposite a – in each ring to keep the ‘scope properly secured: + on the bottom raises the tube, – on the bottom lowers it.

(Don’t use a + against a + as that makes the hole smaller & can damage your scope! A – against a – will leave a larger hole you can’t clamp tightly enough to hold your tube.)

You can use ‘em too for centering your scope laterally if your rail isn’t quite parallel to your bore. They can be rotated anywhere within the rings so a + on the left offsets your scope to the right….

The Burris Signature Zee rings have been the solution to the

dreaded “scope ring damage” for me the last 5 years or so.

Previously, I had been satisfied to match standard Weaver rings

but learned early on to match the top halves of the rings as close as possible to each scope. I even went so far as to use a piece of

Post-It note paper to ease the top ring half over the scope body

to elimnate any evidence of the typical scrub mark(s) as we often

see on used scopes.

Fortunately, I have not had to use the offset inserts to correct a

mis-aligned set of receiver screw holes.

The glass that I have used for 1K shooting that lack the needed

elevation adjustment to get out that far has been solved by using

Ken Farrell`s 20MOA scope bases.

Should someone question how viable the Signature rings are, I can

offer this tidbit…I used the Signaure Zee rings on my Savage LA

in 30-06 with the 190gr and heavier SMK`s with no scope issues at

the Full Bore Prone Rifle League @ Williamsport. (Bodines)

When I choose to offer a scope up for sale that has been used with the Signature series rings, I do not have to include in the description,

“minor ring marks”.

Your first visit at the range with these may take some time, especially

if you need to use the offset inserts to keep your scope adjustments as close to “centered” as possible. The effort is well worth the time spent.

Scott

The off-set inserts saved the day for me, after I had a Shilen barrel mounted on a Ruger #1B. The quarter rib must have been mounted off-center, because windage was radically off to the right. Was able to keep the scope (Leuplod) windage adjustemnt very close to center by using .020″ off-sets in both front and rear rings. The only type of rings I’ve bought, since they became available. Am even using the adapter bases so I can use them on Sako and the before mentioned Ruger receivers. I’ve also noticed that I do not have to tighten down the ring screws as tight as I did with conventional rings. Seems the nylon grips better.

Good job! I have done what you described, as well as combining vertical and horizontal adjustments by rotating the inserts. When you do the latter, the math gets a little more interesting, and harder to explain, but the results can be very worthwhile.

I won’t use any thing else. In fact I’d pick a gun to fit the bases just to use the Signature rings. Get the offset combo pack and have limitless adjustment. They hold tight and can’t booger your scope. Say you need to to bring your crosshair down and to the right, you can install the offset inserts at 45 degrees in the ring. Just a sweet setup.

I looked at the calculation and I see 6″; where did the 3.6″ come from? If you use the formula with 3.6″ spacing and .040″ offset, don’t you get 40″ or 38.2 MOA at 100 yds?

(.040/3.6) X 3600 = 40″ at 100 yds

1 MOA = 1.047″ at 100 yds

40″/1.047= 38.2 MOA

What am I missing?

One thing that I forgot to mention in my earlier comment was that I agree completely with the first comment by Steve Clark. You don’t pair offset inserts of the same sign on the same ring.

OK, I looked at it again and now understand the ‘Note’.

40 MOA * 1.047 = 41.88″

(.040/3.439) * 3600 = 41.87″ (~40 MOA)

Dividing by 3.6 and multiplying by 3600 is the same as multiplying by 1,000. Duh!

If you want a formula that includes different ring spacing, try this one.

MOA = tan^-1(offset/spacing) * 60

Here is the original link from when I worked it up.

http://www.reloadbench.com/ubb/Forum24/HTML/000426.html

Thanks for posting this again. I am working on getting a scope mounted on

Weatherby Vanguard 2 and now know that I need another Pos-Align Insert kit to get everthing set up right. I need a +20 and a -20 instead of a +20 and -10 with the distance between the rings…Damn I like this site.

The NBRSA used inches instead of moa and noted the change, so did John Unertl back then, which was probably the most used scopes of the early years of benchrest. It was explained by the NBRSA and Unertl, however. But to get to the nitty-gritty–Unertl mounts (external) moved the POI 1/4″ @ 100 yards per click on thimbles and each click movement was .0005″ (1/2 thousandths)with a 7.2″ base separation (double the 3.6″ standard above. Here is the formula that has worked for a lot of us for many years using the above criteria: 1.8 divided by base separation x shim thickness (in number of thousandths not actual designation; example 1 instead of .001″) x 2 = POI change @ 100 yards. It works.