Howdy all. I was wondering if there is a link or such for using the Leupold duplex reticle as a rangefinding aid. You know,how much does it bracket at various ranges on what setting. I used to cut 18" cardboard squares in the old days and do R&D in the field,but that was a long time ago with Weaver and Bushnell scopes. Anyone have a lead? Thanks a bunch,R.J.
Leupy reticle ?
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sscoyote
Well-Known Member
R.J.--just use it like u would a mil-dot reticle. Interpolate your tgt. of known dimension between the stadia points in tenths of the total stadia to stadia gap, and then apply the mil-ranging formula using whatever subtension the plex stadia points measure at any distance. I.e. hows about a 10" target that fits between the x-hair and plex post tip at 75% (.75). According to the Leupold subtension pg. in their catalog the Duplex reticle measures 5.3 inch per hundred yds. between plex post tips (i think that's what it is for many of the VX-III models--check it to be sure). That means that it's 2.65 IPHY X-hair to plex post tip. So here's the formula--
10" x 100 yd. / 2.65" / 0.75 = 503 yds.
See how it works?
Play with it some--the more you do the more u'll be able to commit it to memory, and the better you'll understand it's limitations also.
It's important to note that the mil-ranging formula is not specific to the mil-dot subtension. It can be used with any 2 points at one distance relative to the same 2 points at a different distance.
10" x 100 yd. / 2.65" / 0.75 = 503 yds.
See how it works?
Play with it some--the more you do the more u'll be able to commit it to memory, and the better you'll understand it's limitations also.
It's important to note that the mil-ranging formula is not specific to the mil-dot subtension. It can be used with any 2 points at one distance relative to the same 2 points at a different distance.
HARPERC
Well-Known Member
The manual I have in hand states tip of duplex to crosshair is 16" at 200 yards. I don't know about model variations, but I dug a VX-3 out of the safe, it's a model with additional markings on the power select ring, and at 2.5x if you have a 16" target bracketed it's 200 yards, (standard whitetail Beaverton OR, your mileage may vary) on 8x it's 600 yards.
Or 32" tip to tip of duplex post for "elk". This scope is a 2.5-8x.
Your 18" number rang an old brain cell, I suspect sscoyote's numbers may also be correct depending on which generation scope you have, and which model/magnification you use.
This brings full circle the limitations of using variable powered SFP scopes as a rangefinder.
Or 32" tip to tip of duplex post for "elk". This scope is a 2.5-8x.
Your 18" number rang an old brain cell, I suspect sscoyote's numbers may also be correct depending on which generation scope you have, and which model/magnification you use.
This brings full circle the limitations of using variable powered SFP scopes as a rangefinder.
sscoyote
Well-Known Member
Yeah, i forgot to say that the subtension i quoted (assuming it's correct for whatever model you're using) is at the optic's highest power.
Your 2.5-8x is very close to as quoted--
16 x 100 / x" / 1.0 = 600
x=2.67" @8x
It does work to some degree of accuracy though. I've done it a number of times on antelope and a few times on coyotes and found it's definitely better than guessing. Figure maybe 80% acceptable accuracy to somewhere between 400 and 500 yds. depending on angle of subtension vs. tgt. size, and accurate assessment of tgt. size.
Your 2.5-8x is very close to as quoted--
16 x 100 / x" / 1.0 = 600
x=2.67" @8x
It does work to some degree of accuracy though. I've done it a number of times on antelope and a few times on coyotes and found it's definitely better than guessing. Figure maybe 80% acceptable accuracy to somewhere between 400 and 500 yds. depending on angle of subtension vs. tgt. size, and accurate assessment of tgt. size.
AJ Peacock
Well-Known Member
On my 7mm, I have a 4.5x14x40 with a Duplex. I don't use it to estimate range, since the animals are all different sizes, and "guessing" distance at more than 500yds with a scope has too large an error for me for clean harvest.
The one thing I do use the duplex points for is as follows.
Sighted in for 360yds, the tip of the duplex above the crosshair is dead on at 200yds and the lower duplex is dead on at 500yds (at 14x power). I don't remember the dead on distance on low power is somewhere around 800-900yds. The power ring can be marked for specific distances and be very usable as a "ballistic" reticle.
If I recall, the crosshair to duplex on my scope is around 3.5moa at highest power.
Hope this helps,
AJ
The one thing I do use the duplex points for is as follows.
Sighted in for 360yds, the tip of the duplex above the crosshair is dead on at 200yds and the lower duplex is dead on at 500yds (at 14x power). I don't remember the dead on distance on low power is somewhere around 800-900yds. The power ring can be marked for specific distances and be very usable as a "ballistic" reticle.
If I recall, the crosshair to duplex on my scope is around 3.5moa at highest power.
Hope this helps,
AJ
HARPERC
Well-Known Member
I could never get the hang of using the duplex tip that way. There was always something off in my calculations.
sscoyote
Well-Known Member
I had a system established for a 17 MIV XP-100 for awhile that used the plex post tips (PPT) for elevation and windage reference in a 4-12x Burris Mini that subtended 2.7MOA @12x. Had like a 225-yd. zero and the PPT was 340 yds. calcd and tested. 300 yds. was .4 PPT, and 10 mph windage was 1.3 PPT. Killed 2 coyotes with that rig at 300 yds. +/- using the system. One was in a 10 mph measured wind full value, and to hold 1.3 PPT units off into the wind seemed to be quite a bit, but i trusted it and nailed that dog. I'll never forget it.
Went out with a buddy who was using a 4.5-14x Leupy on a rig once and we used it to rangefind a buck antelope while coyote hunting. I had a calculator watch on, and told my buddy to gap it in the reticle (back to brisket) and tell me what he got. he says 1.1 of the X-hair to PPT (2.7 IPHY). The buck lasered at ~500 yds. and here's what he calcd. at using the common measurement of 15" back to brisket--15x100/2.7/1.1=505. The buck wandered on out to ~700 lasered and he did the same thing getting 0.8 PPT--1500/2.7/.8=694. We about fell over. But once u learn to manipulate that equation some u can see just how lucky we were--especially the 700-yd. calc.
Interestingly i've posted this stuff all over the net here and there over the years. I was on a forum somehwere and posted some ? about something and some guy posts a pic of a coyote he killed at 400-something by using the reticle in his optic like a mil-dot that he learned from some of my postings. Yeah it doesn't always work and there are limitations but when u hear something like that it's pretty rewarding.
Went out with a buddy who was using a 4.5-14x Leupy on a rig once and we used it to rangefind a buck antelope while coyote hunting. I had a calculator watch on, and told my buddy to gap it in the reticle (back to brisket) and tell me what he got. he says 1.1 of the X-hair to PPT (2.7 IPHY). The buck lasered at ~500 yds. and here's what he calcd. at using the common measurement of 15" back to brisket--15x100/2.7/1.1=505. The buck wandered on out to ~700 lasered and he did the same thing getting 0.8 PPT--1500/2.7/.8=694. We about fell over. But once u learn to manipulate that equation some u can see just how lucky we were--especially the 700-yd. calc.
Interestingly i've posted this stuff all over the net here and there over the years. I was on a forum somehwere and posted some ? about something and some guy posts a pic of a coyote he killed at 400-something by using the reticle in his optic like a mil-dot that he learned from some of my postings. Yeah it doesn't always work and there are limitations but when u hear something like that it's pretty rewarding.
HARPERC
Well-Known Member
sscoyote
The shortcomings to using the duplex this way were all on my end. Perhaps with a range finder to work out range and then the duplex as a sight pin I might do better. Haven't tried it since laser rangefinders became common.
The shortcomings to using the duplex this way were all on my end. Perhaps with a range finder to work out range and then the duplex as a sight pin I might do better. Haven't tried it since laser rangefinders became common.
sscoyote
Well-Known Member
Yeah--i don't use it much myself anymore really, but it's fun to play with sometimes.
