Leupold range finding scope

[Mike38]

I have a Leupold VX3, 4.5-14x40 on a Remington 700 rifle. This particular scope has a range finding capability. You start with the scope set at it’s lowest setting, aim at a whitetail deer. Slowly increase magnification until the deer body from shoulder to bottom of abdomen fills points of crosshair to enlarged duplex of crosshair. Then look at magnification marks and it will tell you approximately how far away the deer is. Considering that an average adult deer is 16 inches from shoulder to belly. If it fills out marks, and the range finder numbers say it’s 600 yards, which is also 14 power. Then what would the minute of angle be for the scope marks of cross hair to enlarged duplex be? If I am figuring this correctly, the MOA at 14 power would be 2.666. Am I right?

So if I shot this rifle at a target 100 yards away, used the enlarged point of the cross hairs as my point of aim, with the power set at 14. My bullet should hit the target 2.666 inches above center of target, right?

The reason I want to know the MOA of these points is because I want to shoot at 800 yards. I can’t because I run out of elevation adjustment at 700 yards. If I could do a 2.666 MOA hold over, I should be real close at 800 yards. I know, I could buy a 20 MOA scope mount, but I really don’t want to have to do that.

Thanks, and I hope the above makes sense.

[diggler1833]

I may be misunderstanding a bit here.  I will say that I hope you don't think that you can be high at 100yds by 2.666" and be on for anything at 600yds.  Even with a flat shooting magnum...say 7mm family, shooting a 168gr Berger with a high B.C. at a muzzle velocity of say...3000fps.  With being high at 100yds by 2.666" that should put you in the vicinity of a 275yd zero.  That still gives the bullet enough time to drop over 49" before it hits the 600yd mark.  With a 100yd zero it should give you 10.6MOA of drop to 600, and 16.7MOA to 800 roughly.

I can't anwer your question because your calculations seem off, and I'm not sure that I'm understanding right.  Best bet is to get a decent range finder, and shoot the distances that you want to...then get your come-ups.

[Mike38]

I don’t think it’s you misunderstanding as much as it is me not explaining it correctly. Let me try again.

I am trying to determine what the minute of angle is between the crossing point of the vertical and horizontal reticule lines, to the part where the duplex gets larger. Think of it as the first dot down (first dot of elevation) in a Mil Dot scope. I realize this changes as the magnification changes, for sake of argument, let’s say my scope remains at 14 power.

Look at it this way. If a16 inch target (or deer’s body, or shoulder width of a human being, or a 16 inch diameter circle) fills in the area from the crossing point in the reticule, to the point where the duplex gets larger. The known distance is 600 yards. 16 divided by 6 equals 2.666. So a 16 inch target at 600 yards covers 2.666 minutes of angle. Is that correct?

Side note: I know 2.666 MOA will not be enough elevation to get me from 100 to 800 yards (it‘s somewhere around 16 MOA). But it will get me from 700 to 800 yards. Not precisely, but it will get me on the paper. I can elevate my scope with the knob enough to get me out to 700 yards then I run out of elevation. I’m trying to determine if I can use the duplex cross hair point to get myself another little bit of elevation, much like how you would use a Mil Dot scope.

Again, I’m sure it’s not you, it’s the way I am explaining it that makes it confusing.

[Catfish]

I am a Leupold fan, but would never use one of these scopes for a range finder. Since you can never be sure that a deer is exactly 16 in. and the error in focus your distances will only be fairly close. With all of the lazer range finder on the market that will put you within 1 yrds. why use out dated technoligy.

[diggler1833]

MOA = 1.047" at 100yds so you would be fairly close at the 2.666 but not right on.  The 2.666 would actually be correct around the 628.2yd mark.

[sscoyote]

If u bracketed the 16" target perfectly between the X and the 2.666 MOA (2.79") plex post tip (at 14x) it would actually be--

16 x 100 / 2.79 (") / 1.0 = 573 yds. away

Now according to the catalog the actual measurment is 2.7" (5.4/2) @ 14x,

so then--1600/2.70/1.0=592

a whopping 9/100's of an inch subtension gives a 20-yd. error at that range.  This is why i reticle-range to about 500 yds. and call it quits for any degree of accuracy beyond that...on game (except prairie dogs/chucks--since it's always better than guessing).

You may notice that the above equation is actually the mil-ranging formula with a plex reticle subtension sustituted where the 3.6" measurement would be--IMPORTANT TO UNDERSTAND (IMO), since "mil-ranging" is not specific to the mil-dot, and can be accomplished with any stadia to stadia subtension measurement.

[sscoyote]

Mike--if u wanna' play around with rangefinding with plex reticles, don't use Leupold's RES (range estimating) as designed. Use the "modified" mil-ranging formula as detailed above--it's way more flexible and accurate, IMO.

I often use plex reticles for downrange zeroing and windage reference--especially in the cheaper lower-powered optics, as the subtensions are usually larger and can be applied well that way.