Ranging Practice discussion thread (spoilers)


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taliv
August 16, 2010, 03:02 PM
Please use this thread to discuss the ranging practice challenges (http://thehighroad.org/showthread.php?t=539037). Reference the challenge by post number.

If you need a refresher on the formulas try this link
http://www.scribd.com/doc/2069052/Mil-and-Moa-Range-Formulas-for-different-Combinations

And if you need basic instruction, try this software http://shooterready.com/

--------
Challenge in post 3
1858, assuming your large hashes are 1mil and capt rustbeard there is 30" tall, i'd range it at 500m, but .7mil was my dope for 300 yrds (100 yrd zero)....OH, i just saw you said .7 was your windage... i misread that as your comeup

What (shooting) range was that at?

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Maverick223
August 16, 2010, 03:21 PM
No answers?...or no guesses either?

Obscure the actual range between the words "START" and "STOP" and change the color of the text to white, which will be invisible until readers highlight it.That doesn't work if you have THR set to shaded background. In other words I can see the answers. :(

taliv
August 16, 2010, 03:26 PM
no discussion in the other thread. just pictures.

That doesn't work if you have THR set to shaded background. In other words I can see the answers.
well, close your eyes then :) edit: seriously, if you have a alternative suggestion, plmk

are you measuring to the bottom of the wood? or the bottom of the rust to get your 600 yrd answer? (edit: you could be right.. i don't know yet)

Maverick223
August 16, 2010, 03:32 PM
are you ranging to the bottom of the wood? or the bottom of the rust to get your 600 yrd answer?Bottom of "Cap'n Rustbeard"...assuming about 36in. target size, and doing the math in my head so I am probably off by a fair margin.

P.S.: Would you mind adding the targets to this thread as well (less the answers)? This promises to be a fun little challenge.

:)

baldeagle93
August 16, 2010, 06:29 PM
I like the challenge, but would prefer the target to be captured at a good mil position.

I got the first one, the second one is a little more tricky due to not knowing exact target size or familiarity with MOA reticle. I am going to assume that it is a typical man size target like the first. By my calculations...and I could be way off, but I got 740 yards.

Like my teachers always wanted...I'll show my work :scrutiny:

Known Data
TZ = 40"
Mils = 1.5

40"/36"=1.11

1.111 x 1000 = 1110

1110 / 1.5 mils = 740 yards

anyone agree??? :cool:

Maverick223
August 16, 2010, 06:48 PM
I'm going to revise my answer and go with 650yds. Initially it looked to be about 1.6mils, but now I see the "top of the head" isn't flush to the hash, making it right at about 1.5mils. Still assuming a 36in. target, milling reticle, and FFP (or at the correct magnification).

:)

baldeagle93
August 16, 2010, 06:56 PM
So our "known" target size is the only thing separating our calculations...that's good to know.

Does the OP know what the true distance is???

Good to back on...works been busy (about time!) and its been too hot to shoot and since the rim fire challenge distance changed I can't take advantage of the indoor range :( Now it's too hot to shoot and too hot to enjoy my other hobby, riding my motorcycle!

LemmyCaution
August 16, 2010, 07:02 PM
Regarding post 2:

Assumptions:

1: Mil Dot reticle
2: 1 meter high target
3: FFP reticle or set at proper magnification

Estimation:

Height of target is 1.1mil

Answer:

Range is 909 meters.

LemmyCaution
August 16, 2010, 07:04 PM
Regarding post 3:

Assumptions:

1: 1mil between major stadia lines
2: 1 meter target height
3: FFP reticle or set at proper magnification

Estimation:

Height of target is 1.5mil

Answer:

Range is 667 meters.

Maverick223
August 16, 2010, 07:16 PM
So our "known" target size is the only thing separating our calculations...that's good to know.Yep, pretty much...along with the fact that I was too lazy to get a pen and paper so I did the math in my head and rounded a few things (negligible IMO because there wasn't sufficient significant figures from the guestimation of target size to make a worthwhile difference).

:)

taliv
August 16, 2010, 07:21 PM
this is going to be even more entertaining than i first imagined :evil:

I'm going to go take a bunch of pictures this week of non-standard-sized-targets.

Maverick223
August 16, 2010, 08:09 PM
I'm going to go take a bunch of pictures this week of non-standard-sized-targets.Evil, you are! http://forums.nitroexpress.com/images/graemlins/smilies/general/stir.gif At least give us something (a car, tree, person, et cetera) for scale.

:)

baldeagle93
August 17, 2010, 08:45 AM
Then make sure that you have something identifiable in the picture to determine...oops, guess Mav beat me to it!

At least give us something (a car, tree, person, et cetera) for scale.

Tim the student
August 17, 2010, 10:50 AM
Cool thread here!

1858
August 17, 2010, 02:50 PM
EDIT: Images moved to sticky thread HERE (http://www.thehighroad.org/showthread.php?t=539037)

I measured myself and I'm right around 40" from crotch to crown so the rusty steel targets shown could be considered representative of a 6' male.

:)

blackops
August 17, 2010, 03:23 PM
post 4 first pic, 660yds.

1858
August 17, 2010, 03:57 PM
post 4 first pic, 660yds.

In this case, if you were aiming at the center of mass using a typical .308 Win and estimated the target to be at 660 yards, you would have missed the target (center of mass) by something like 50" or just over 4'. That's not even taking into account the wind call. As one instructor told me, every miss educates your opponent!

Added in edit: I've missed lots of targets even when I knew the range to within a few feet so I'm definitely not trying to be a wisea$$. I'm just making the point that without a laser range finder, range estimation can be very difficult, particulary when you have to estimate the size of the target. Under these conditions, we can miss by A LOT!!

:)

taliv
August 17, 2010, 04:06 PM
TIP: Target is representative of a "typical" man if measured from crotch to crown. The target is not at exactly the same range as the target in post #3.


really? cause it looks exactly the same, just at a different magnification

i guessed 333 yrds on the guy in the middle in the back on pic #2 in post 4
and 277 yrds on guy on the right in pic #3

1858
August 17, 2010, 04:13 PM
really? cause it looks exactly the same, just at a different magnification

The two targets in question are at similar ranges but seperated by something like 12" of bullet drop which may or may not make a difference. This is based on range data using my Swarovski Laser Guide. I'm going to head out to the range this week to try to get some better photos and look for other interesting targets.


i guessed 333 yrds on the guy in the middle in the back on pic #2 in post 4

Did you assume a "typical" head size and then estimate the total height of the target?

:)

baldeagle93
August 17, 2010, 06:44 PM
Target size-Head = 12" (probably more like 10" which will make my yardages about just under 17% high :banghead: ...oh well, here goes nothing!)

Target #1 (which is actually third picture)

Tz= 12"/36" = .333
.333 x 1000 = 333
333/1.5 mils = 741 yards

Target #2 (picture #4)

Charlie on the left
Tz= 12"/36" = .333
.333 x 1000 = 333
333/1 mils = 333 yards

Charlie in the center
Tz= 12"/36" = .333
.333 x 1000 = 333
333/.7 mils = 475 yards

Charlie on the right
Tz= 12"/36" = .333
.333 x 1000 = 333
333/1.8 mils = 416yards

Charlie on the right bottom
Tz= 12"/36" = .333
.333 x 1000 = 333
333/1.3 mils = 256 yards

Target #3 (picture #5)

Tz= 12"/36" = .333
.333 x 1000 = 333
333/.8 mils = 416yards

taliv
August 17, 2010, 07:32 PM
Yeah I guessed typical head was six inches and measured ear to ear not by the hat

edit: i didn't use the head to measure the body and then range on the body, if that's whta you're asking, since i assumed the mounds in front were variable heights

LemmyCaution
August 17, 2010, 07:59 PM
Post 4, No.1:

Man sized target is 0.5 meters across the shoulders. I estimate 0.7mil across the shoulders.

(0.5/0.7)1000=714 meters.

Post 4, No.2

Head of man sized target is 0.25 meters high. We'll scale it by 0.9, given your admission that the targets are not full scale. I estimate 0.7mil as the head height.

(0.25(0.9)/0.7)1000=321 meters.

Post 4, No.3

Ranging off upper body this time. Same 90% scale factor. I estimate 2.5mils crotch to top of head.

(1(0.9)/2.5)1000= 360 meters.

I see from the hidden answer that it's actually 275 meters. I can't make that work, no matter how I estimate it.

So I start over, ranging the head this time.

The head looks to be 0.8mil.

(0.25(0.9)/0.8)1000= 281 meters. Close enough for anti-government work.

blackops
August 17, 2010, 08:35 PM
1858, i was taking a 308 with a 2 moa spread in your reticle (which would equal 6 moa) with a 40" target (typical size of a human torso) Maybe I missed a few things since Ipicked up this thread from my phone, but knowing the reticle measurments for your PR would make things much easier.

LemmyCaution
August 17, 2010, 08:54 PM
Blackops-

All the reticles in the exercises thus far are based on angular mil, not MOA. The major hash marks in 1858's reticle are 1mil apart. The minor hash marks are 0.5mil.

1mil = ~3.44 MOA.

blackops
August 17, 2010, 09:02 PM
Lemmy, 10-4. I knew I was missing something there. Easy to overlook things from the cell. I was like, no way I would be off by 4 ft. No wonder were playing with mils. I like MOA better myself.

LemmyCaution
August 17, 2010, 09:50 PM
I like MOA better myself.

I guess if you're going to measure distance in something as archaic and impractical as inches, feet and yards, you might as well really shoot the moon and measure angle in MOA.

I like math… but not that much.:)

sscoyote
August 17, 2010, 10:52 PM
Man--i love it. Would've liked to have seen the little 27" army men on top of the TMR reticle closer to the .2 mil stadia lines to get a more accurate interpolation. Actually got 333 once i knew the tgt. dimension (not bad for interpolating both sides of the tgt.). Got 896 on the thousand yarder, but was happy about that due to the inaccuracy of the system (for me at least) beyond ~500-600 anyways as well as 2-sided interpolation as well.

Don't understand how to post a pic though to get the answer into a ghostlike format..?

taliv
August 17, 2010, 11:35 PM
so post number 5...

interesting challenge. i figured the target was 2/3 larger than it ought to be, so i measured it as 2 mil wide (though it looks kinda funky like it's at an angle or something) so i figured that was 1.333 mil. 1/3rd of a yard high divided by 1.333 mil * 1000 gave me 250 yrds. but if i did that on height, using 2/3 of what looks to be about 1.6 mils, gives 312 yrds. hmm...

LemmyCaution
August 18, 2010, 06:04 AM
Post 5:

Step 1: De-Americanize the units: 12" = ~0.3m
Step 2: Un-ass the SFP scope: 12/18 = .666
Step 3: Estimate target width = 2mil
Step 4: Apply un-ass factor: 2(.666)= 1.332
Step 5: Math (0.3/1.332)1000= 225 meters

This is apparently wrong. So the target is 12" what? High? Wide? Viewed from an oblique angle after three beers while squinting?

Let's try 12"H. I estimate 1.65mil (I think I see 0.05mil of rock sticking down below the crosshair).

1.65(.666)= 1.1
(0.3/1.1)1000= 273 meters (298 yokel meters)

There we go.

sscoyote
August 18, 2010, 12:42 PM
Well done--nothing wrong with using 2nd FP reticles for rangefinding, especially since about 99% of us use them. It teaches an important concept of the inversely proportional nature of subtension vs. magnification. Besides that rangefinding is more accurate at a higher magnification and smaller subtension. If all the user has is a 2FP scope then he may as well know how to apply it. In fact i have used the mil-reticle in a 2FP optic at 32x to reverse mil a tgt. of known dimension to calculate a subtension in order to reverse mil a 1000-yd. target to obtain it's dimension, and guessed it to within .3" of it's true dimension.

The target is setting at a slight angle, but from my calcs on this 1 and others it doesn't seem to be enuf to make a difference.

BTW, the .05 below was absolutely correct. Excellent observation!

Just noticed that width doesn't seem to work on this one, and i don't know why as it is a 12" disc.

baldeagle93
August 18, 2010, 02:03 PM
Just noticed that width doesn't seem to work on this one, and i don't know why as it is a 12" disc.

I think it is because the target is at an angle which is giving you an inaccurate mil reading.

I guess if you're going to measure distance in something as archaic and impractical as inches, feet and yards, you might as well really shoot the moon and measure angle in MOA.

I don't think that anyone here would be considered a "Metric Martyr," but the "impractical" imperial system is what we are used to. The target is at the same distance not matter what, you have to do math to get the range.

LemmyCaution
August 18, 2010, 08:01 PM
The target is at the same distance not matter what, you have to do math to get the range.

You just have to do a little MORE math in the American system (We don't actually use the true Imperial System. the UK does) Actually, kind of a lot. Actually, too much, unless you just let the computer take care of the whole thing. And how ironic that a country like ours uses the facets of the king's anatomy as the basis for our measurements. But I mean really… An inch is ~0.02778 yards! A foot is 0.3333333333… yards! Preposterous!

Full disclosure: I speak the American system very well. I work in the trades. But I also used to manufacture power systems for the oil and gas industry internationally, and I have to say that the SI system is far superior.

There's almost nothing more silly than a decimal inch. Almost, meaning a metric foot (http://en.wikipedia.org/wiki/Metric_foot). I once received a truss system from a manufacturer in the UK. The overall lengths of the truss sections were in even metric increments. The weldment of the truss webs, center to center, was in feet. The results were comical (Q: 'how many feet fit in 2 meters?' A: 6, remainder 6.74 inches). But the manufacturer insisted that their product was not merely of the highest quality, but 'superior.' And not just superior to this or that, but just simply 'superior.'

1858
August 18, 2010, 08:13 PM
sscoyote,
Here's what I get with your 12" high target.

milrad (vertical) = 1.55 but reticle calibrated for 12x not 18x
18/12 = 1.5
milrad_actual = 1.55/1.5 = 1.03 milrad
12" = range(")*0.0013(radians)
range (yards) = (0.0013/12")*(1 yard/36")
range = 322.6 yards

On closer inspection, I'd estimate the vertical subtension to be 1.60 milrads rather than 1.55 milrads. This would result in 312.5 yards ... not a bad estimate.

:)

sscoyote
August 18, 2010, 09:12 PM
Excellent. Kinda' nice when it works. Must be the angle that is actually making the difference between height and width. I'm certain that i measured the vertical along the face of the plate at 12", but it could be oblong. I'll check it again next time i go out to the range. We also have another couple plates set at 425 yds. again at an angle. A buddy was checking his MD-reticled 3.5-10x Leup. M4, and it wasn't coming out right. I looked through it and got just short of 1.2 mils at a guess of 1.18-- 18 x 100 / 3.6 / 1.18=424. Worked perfect and my buddy about fell off his bench.

LC-- Don't understand what the big deal is here. Heck man we're just calculating ranges to tgts. using a reticle. It's not like we're paying the mortgage--relax.

Maverick223
August 19, 2010, 02:43 AM
I once received a truss system from a manufacturer in the UK. The overall lengths of the truss sections were in even metric increments. The weldment of the truss webs, center to center, was in feet. The results were comical...I don't doubt it, a friend of mine worked on a bridge project with metric specifications (design), the construction (being performed in the US, WV IIRC) was performed using the imperial system [head slap]. Several errors (blunders) led to major sections of the work having to be demolished and rebuilt...a very costly mistake that could have easily been prevented by using the same standards for measurement in the design and construction. It turned out something like this (obviously not the actual project, but a good, if exaggerated, example):

http://www.myconfinedspace.com/wp-content/uploads/2007/06/little-mistake.jpg

:)

Dimis
August 19, 2010, 03:47 AM
are we going for exact or just rounding it?

baldeagle93
August 19, 2010, 09:59 AM
LC,

how ironic that a country like ours uses the facets of the king's anatomy as the basis for our measurements

Could not agree with you more! I mean we fought for independence through the revolutionary war and we forgot to change one important facet of our freedom...freedom from silly decimal inch.

Just poking fun...I actually agree with you, but it is the standard for America and when in Rome...

Mav has a very good point and I just alluded to it...standard. It should not mater if you were measurements are taken in cubits as long as you are using it as a standard. Just my humble opinion...I could be wrong, it happened once.

Maverick223
August 19, 2010, 01:25 PM
It should not mater if you were measurements are taken in cubits as long as you are using it as a standard.Yep, which leads to a good point...the adjustments should absolutely match the reticle...No Matter What. If you like to turn knobs in MOA, no problem, get an MOA reticle...like Milling reticles, get Mil knobs to match.

:)

1858
September 25, 2010, 11:04 PM
taliv,
I was +11 yards on the left plate (est. 0.3 milrad) but +133 yards on the right plate (est. 0.25 milrad)! An error of 133 yards at that range is significant.

:)

taliv
September 25, 2010, 11:10 PM
man, nice work on the first one! that's close!

i posted 2 more, btw

1858
September 26, 2010, 11:59 PM
taliv, are you sure about the target in post #10? Either way, this method is not proving to be too accurate for me and I used a ruler this time.

Post #8: +33 yards on the right target :cool: and +110 yards on the left target :eek:

Post #9: +97 yards :eek:

Post #10: +445 yards :what:

Post #11: -160 yards :eek:

:)

Grump
September 30, 2010, 02:38 AM
Taliv:
I really don't buy it on the 1000 yard target, second to last of of today. Post #10, September 25, 2010, 07:17 PM. I see the 12-inch square as being a bit *more* than the 0.5 mil hash mark. I called it .6 mil.

.333 yard target (1 foot square) divided by .6 mil = .555 x 1000 = 550 yards. Or are those .25 mil hash marks and I'm 10% off on the mils? Or is there an undisclosed SFP discrepancy?

It would have to subtend .333 mil to be at 1,000 yards, by my math.

Please 'splain.

I GOT the one with the SFP set at 18 power...IN MY HEAD, no calculator!.

taliv
September 30, 2010, 07:28 AM
Hmm. Could be wrong. We shot that plate from lots of distances and angles up to a mile away. I was taking pics with my iPhone and had no way to label them until I got home. So yeah it's entirely possible I mixed one up. I'll look them up Saturday and verify.

Great work on the rest especially considering the quality of photos

Edit. One thing to note with my pics is that I'm not always square to the target so if it is at an angle it could appear narrower than it actually is making it appear further away but vertical should be correct

taliv
September 30, 2010, 07:47 AM
Doh! You guys were right. We shot that at 1020 yrds from one stage and 585 yrds from another. I put the wrong value in the main thread and will fix it shortly. The correct range is 585

blackops
December 3, 2010, 10:33 PM
All I have to say is I wish targets were that clear at 1000yds in my scope. It would be an entirely different ball game.

taliv
December 11, 2010, 10:57 PM
man, good luck with challenge in post 15! anyone who gets within 10% will deserve a cookie for sure.

i was right on measuring the dude in post 14 vertically, but i'm way off when i measured him horizontally.

~Ace~
December 23, 2010, 10:30 AM
On the Last Pic I get 800, 860 and 900 using my new Ipod App.

taliv
December 23, 2010, 12:05 PM
wow, Ace, that's pretty close!

what ipod app lets you do that??

B1gGr33n
January 17, 2011, 02:37 PM
Man I've got lots of learning to do :( lol

taliv
March 18, 2011, 08:12 PM
I can't wait to see who gets the bonus target in post 21!

sarduy
August 27, 2011, 08:59 AM
Post 21 turkey = 666 yards?

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