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Hank45 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hank45 Quote  Post ReplyReply Direct Link To This Post Topic: recticle
    Posted: August/10/2010 at 07:35
What does a ranger recticle look like?  Thanks for your answer, Hank45
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 8shots Quote  Post ReplyReply Direct Link To This Post Posted: August/10/2010 at 08:17

Could you be referring to a "ranging" reticule??

A ranging reticule can be one of several, of which a mildot and the BDC are the most recognized. In each case the size of the target must be known for the maths to work.
 
By knowing how many mills the target is when looking through the scope and the size of the target the distance can then be calculated.
Example:

To determine the distance to a target of known size: (Distance in yards) = 1000 / 36 x (Object size in inches) / Mils

To determine the size of a target at a known distance: (Object size in inches) = 36 / 1000 x (Distance in yards) x Mils



Edited by 8shots - August/10/2010 at 08:20
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cyborg Quote  Post ReplyReply Direct Link To This Post Posted: August/10/2010 at 11:52
Good follow there Wouter.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cyborg Quote  Post ReplyReply Direct Link To This Post Posted: August/10/2010 at 12:00
Here's even more info for the next question that will be coming soon.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote stickbow46 Quote  Post ReplyReply Direct Link To This Post Posted: August/10/2010 at 18:55
Every time I see the equation I still get confused with the numbers,let me explain, if we are doing the math in mills[39"]why do they use the figure in yards[36"].I think the Marines covert to yards as opposed to mills & that # is 27.7777x target height in inches over # of mills the target covers?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 8shots Quote  Post ReplyReply Direct Link To This Post Posted: August/11/2010 at 02:35
Originally posted by stickbow46 stickbow46 wrote:

Every time I see the equation I still get confused with the numbers,let me explain, if we are doing the math in mills[39"]why do they use the figure in yards[36"].I think the Marines covert to yards as opposed to mills & that # is 27.7777x target height in inches over # of mills the target covers?
 
I think it is an ease of reference thing for the American world. The rest of us use metric as in meters. So 1mil is actually 1 meter at 1000m which is close enough to 1 yard at 1000 yds.
So 1 mil becomes approx 3.6 inches at 100yds.
and 1 mil becomes 3.9 inches at 100m
 
It is all in the metric v's the imperial.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Urimaginaryfrnd Quote  Post ReplyReply Direct Link To This Post Posted: August/11/2010 at 03:07
Originally posted by Hank45 Hank45 wrote:

What does a ranger recticle look like?  Thanks for your answer, Hank45
Isn't that the old one with the hitching post and crossbred mare?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 8shots Quote  Post ReplyReply Direct Link To This Post Posted: August/11/2010 at 04:19
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Post Options Post Options   Thanks (0) Thanks(0)   Quote stickbow46 Quote  Post ReplyReply Direct Link To This Post Posted: August/11/2010 at 08:48

Thanks 8,now I know I'm only part crazy [:}

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Post Options Post Options   Thanks (0) Thanks(0)   Quote jonoMT Quote  Post ReplyReply Direct Link To This Post Posted: August/11/2010 at 10:27
mils are not to be confused with the metric system. The only similarity is that both (coincidentally) happen to use a decimal base. A mil(liradian) is 1/1000th of a radian - an measurement of angle, not distance. So 1/1000th of 1000 inches is 1 inch, 1/1000th of 500 yards is .5 yards (18") and so on. My preferred way of doing the math is:

1) multiply the target size X 1000, e.g. 18" = .5 yards * 1000 = 500

2) divide that number by the number of mils, e.g. 500 / 1.7 mils = 294 yards
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Post Options Post Options   Thanks (0) Thanks(0)   Quote stickbow46 Quote  Post ReplyReply Direct Link To This Post Posted: August/11/2010 at 17:15
Thanks jono but I know have another question;multiply the target size is that size done in meters or inches ?Again thanks!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 308 Sav Quote  Post ReplyReply Direct Link To This Post Posted: August/11/2010 at 21:15
If you want to range in meters then use a know metric mesurement for the object.
If you want to range in yards use imperial measurements for the object.

KISS
Keep It Simple 

I can remember 27.77 so I use to find range

  Object’s known size (inches) x 27.77  

        Object’s scoped size (mils)

  

Or


 Object’s known size (yards) x 1000                       

        Objects scoped size (mills)

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 308 Sav Quote  Post ReplyReply Direct Link To This Post Posted: August/11/2010 at 21:17
That is ranging in yards
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Post Options Post Options   Thanks (0) Thanks(0)   Quote stickbow46 Quote  Post ReplyReply Direct Link To This Post Posted: August/11/2010 at 22:46
Thanks to all
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billyburl2 Quote  Post ReplyReply Direct Link To This Post Posted: August/15/2010 at 12:30
Originally posted by stickbow46 stickbow46 wrote:

Thanks jono but I know have another question;multiply the target size is that size done in meters or inches ?Again thanks!
  Yes. Depending on whether you want the solution in yards or meters. The mil is not a linear unit of measure. It can be converted to any unit of linear measure needed to dial for the shot.   Plus 1 for 308 sav
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jonoMT Quote  Post ReplyReply Direct Link To This Post Posted: August/15/2010 at 17:22
One reason I prefer the formula that multiplies the object's size in the same units, e.g. .5 yards X 1000 (yards) divided by number of mils is that, unlike the 27.78 constant or other variations, you can also use that with meters or any other unit you might care to employ, e.g. .5 meters X 1000 (meters) divided by number of mils.

Another thing about that method I find helpful is that my first result (multiplying the object's size by 1000 of the same units) is the distance the object would be @ 1 mil, e.g. an 18" target is .5 yards X 1000 = 500 yards. Now I instantly know that if the number of mils is less than 1 my final result will be  a longer distance. Or, if greater than 1, the target is closer than 500 yards...cuts down on errors for me. There are some numbers that have easy reciprocals, e.g. 2 & .5, 3 & .33. Inside of 500, since ballistics tend to be more forgiving, you could estimate more often. For example, let's say you milled 1.8 on that .5 yard target. You remember that the reciprocal of 2 is .5, which would give you 250 yards. Now fudge a little and call it 260 or 270 and you wouldn't be far off from the actual result of 278 yards. Even if I didn't bother, the difference for my .308 load is around 2.5" between 250 and 275 yards. The farther out you go, of course, the tighter your estimate better be.

Bear in mind that estimating range with a reticle is plain hard. I do it out of interest and as a backup to laser ranging. But you've got to have a decent grasp of the math and be able to get a clear, steady sight picture. I find when I move to my highest magnification setting (15X) I can't even do it without either a good prone rest on a bipod or something like a log or fencepost.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sscoyote Quote  Post ReplyReply Direct Link To This Post Posted: August/22/2010 at 23:41

Interesting postings and fun to play with the math, IMO.

When i 1st started playing around with the MD for rangefinding, i kept seeing this 27.78 factor, and couldn't figure out where it came from. When i found out it was just the range of subtension measurement to subtension itself (100/3.6) that turned on a light bulb in my head (dim though it may be). I thought to myself why couldn't it be used with any subtension, like a plex reticle, or ballistic reticle like Burris's Ballistic Plex. Well turns out it does work, just fine, sometimes even more accurately than the milliradian itself.
 
Several years ago my buddy was using his VX-III 4.5-14x with plex reticle for his coyote rig. We were taking a break one afternoon and a herd of antelope came by. I told him to bracket the buck in it, and tell me what the reading was. He ranged at ~500 lasered. He said it occupied 110% x-hair to plex post tip (2.7 inch per hundred yds. which is the std. for many of the VX-III models). So i punched it into the most basic form of the mil-ranging formula figuring 15" back to brisket (avg. buck)--
 
15 x 100 / 2.7 / 1.1 = 505 yds.
 
They made their way out to ~700 lasered so i told him to do it again, and he got 80% (0.8)--
 
1500/2.7/0.8=694
 
This was really a huge epiphany for me when i found out that the mil-ranging formula wasn't specific to the mil-dot reticle, and opened up a door that is way bigger than mil-ranging with the MD reticle alone.
 
Another important aspect of "mil-ranging" with the mil-ranging formula is that it also defines downrange zeroing with any reticle or turret system as well, since if u think about it a bullet drop referenced through an optic is the same sort of measurment as a tgt. size. Suppose u want to know how many MOA to put into your scope for 54" drop at 633 yds.--
 
54 x 100 / 1.047 / x = 633
 
x=8.1 MOA
 
IMO, once the shooter has a complete understanding of the MR formula and the inversely proportional nature of magnification vs. subtension in 2FP reticles a world is opened up to the shooter comparable to what reloading does for the shooter.
Steve
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billyburl2 Quote  Post ReplyReply Direct Link To This Post Posted: August/23/2010 at 00:29
Good math, SS. But it would be even easier with a First Focal plane scope, as the reticle sub-tensions would remain the same across the zoom range. But with Second Focal Plane scope, they would either only be correct at one mag(usually the max) or you would have totally map out your scope to see if the labeled magnification was correct. Plus adding another level of complexity to the math.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sscoyote Quote  Post ReplyReply Direct Link To This Post Posted: August/23/2010 at 02:43

No question about it Billy, FFP is easier, but at least it gives u an option if you have 2FP scopes with plex or ballistic reticles on other rigs.

Steve
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