Forgive me..kinda confused!!

L

LivetoHunt2008

Guest
Okay...I read this tech tip..I am still confused..do I use 1/2 half of the Burris insert for the front and rear?..or both "pairs" to gain 20MOA..

their tip states +0.020" and -0.020"

Thanks...

This is what I have:

For use with Burris Signature Rings

Burris Item # 626019

Tube Diameter: 1"

Kit includes +or- .005, .010, and .020 offset Insert sets.

(1 + and 1 - of each.5, 10, and 20)
Click to expand...

TECH TIP: Burris Signature Rings — Calculating Actual Elevation Changes
Filed under: Optics, Tech Tip — Tags: Burris, Insert, MOA, Rings — Editor @ 11 am
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 explained this recently 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.
Click to expand...

burrissigsx350.jpg
 
Last edited by a moderator:
most folks use bases to gain that elevation- not a fan of those rings. but anyway, the -20 is a matched pair and the +20 is a pair. the matched pair stays together- one complete in the front and one in the back. if you seperate them you'll have like a lower half designed to keep the scope straight and the top half trying to run the tube down hill. so you need a +20 set and a -20 set. you can't throw a -20 half in the back and the other half in the front.
 
Like Dusty said.

The pairs of inserts are supposed to be kept together, but you can use a +20 in the rear and a -20 in the front to give +40 MOA. To gain 20 MOA use a +20 set in the rear ring and a 0 set in the front. Or a +10 in the rear and a -10 in the front.

Unlike Dusty though, I like the Signature rings and inserts on rifles that may have had the screw holes for the scope bases drilled out of line. I've got one rifle that needs about 30 MOA of windage to get centered on the target. The only alternatives are redrilling the holes or a Redfield style base with windage adjustment on the rear. The Signature rings allow the adjustment without the possibility of tweaking the scope tube.
 
..what confused me was this picture [see red ellipse]


burrissigsx350.jpg
 
Many years ago, before I'd ever heard of such factory inserts, a friend suggested using strips of very fine mesh cut from a sheet of the material he had found at his job at a chemical plant, as inserts to prevent scopes shifting under heavy recoil.
Later on a gunsmith friend mentioned having a problem getting enough elevation for one thousand yard shooting with a rifle brought to him.
Even with some radical reworking of the bases he still hadn't got it zeroed in.
I suggested he add the fine mesh inserts to pull double duty, adding one or two extra layers under the rear of the scope.

The mesh used is about as thin as a sheet of paper, stainless steel of some sort. Very tough and cuts cleanly.
Near as I can figure it was used to strain chemicals, or slurries, at a nylon factory.
 
these are about the best you can use on a varmint rifle.

you guys have me confused and i have used them for years.

however i think you should re read the directions that come with them.
a set is a pair that consists of a -20 and a + 20 and they are to be used together in one ring. two minus 20 inserts do not go toether nor do two plus 20 inserts go together in the same ring.

perhaps you understand how they work but did not state it properly. to get 20 moa you put a minus 20 on top and a plus 20 on the bottom of the rear ring. use a 0 in the front. that is 2 zeros together.
if you want more you can use the front ring and put a plus 20 on top and a minus 20 on the bottom for a total value of 40.

now if that is not enough deliberately mismatch a set of rings and put a medium ring in front and a high ring in the rear and get a bunch more.
 
Don't know if they still use these but I remember a fellow rectifying his rings by use of a reamer made for the purpose.
The reamer was the same maximum diameter as the scope tube. You'd set the reamer inside the rings oriented at the angle you wished the scope to be, then turned the reamer by hand as you tightened down the upper half of the ring.

I've also seen rings that had a curved inner surface and inserts that were curved on the outside to match. This would allow the scope to be mounted without binding even if the rings were mounted at differing heights. Such as a rear base shimmed to raise it a bit.
 
Bad practice...

Old Gunner said:
Even with some radical reworking of the bases he still hadn't got it zeroed in.
I suggested he add the fine mesh inserts to pull double duty, adding one or two extra layers under the rear of the scope.
Click to expand...

It is a bad practice to insert a shim under a scope using normal rings. Tightening the scope rings after a shim insertion under the scope in either the front or rear ring will usually result in a dented scope tube at the non shimmed scope ring location due to a different angle between the front and rear ring. The Burris signature scope rings with the movable inserts eliminate this by moving at the same angle (gimble action) as the ring insert modification.

These rings are a very reasonable priced solution for long range shooting for the average shooter.

virg
 
You must log in or register to reply here.
Back
Top