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Vortex Viper BDC like Swarovski?

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/12/2009 at 00:02
Couesfanatic View Drop Down
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I'm trying to calculate distance for the reticles on my Vortex Viper 4-12x40. My dad and I recently worked out some kinks on his Swarovski scope.  Swaovski has a program on their website where you can calculate the reticle distances for his exact gun and cartridge. Is there any program like this for Vortex? I can't find a way to figure out what the yardages are for my mil-dot reticles are beside burning tons of ammo. Any help?
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basically I want to do what Swarovski does on the third post on this page:

http://www.opticstalk.com/forum_posts.asp?TID=5024
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/12/2009 at 08:49
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If you know the flight path of the bullet, you calculate the correct holdover. You can get the flight path for the bullet by mapping the flight path yourself by shooting at different distances or calculate it with a ballistics software if you know bullet weigth, bullet ballistic coefficient and initial velocity. For example Norma´s website has a free ballistic software.
www.norma.cc

When you know the flight path, you can calculate how many dots you need to take correct amount of holdover. The distance between dots is 1 milliradian, which is 10cm@100m, which is exatcly 3.6"@100 yards. Now you divide can this 3.6" with 100 yards and multiply it with the desired distance, so you get -> 7.2"@200yards and 10.8"@300yards and so forth.

Let´s say you have zeroed you rifle at 150 yards and the bullet drop is -27.3"@ 400yards. 1 mil is 4*3,6" = 14,4"@400 yards.  27.3/14.4 = 1.9, so correct holdover is 1.9 mil radians. Because the diameter of a dot is usually somewhere between 0.20-0.25mils, depending on a scope, you would have to take aim with top end of the second dot downwards.

Of course you have to keep in mind that Vortex Viper is a second focal plane scope, so adjusting magnification will change the space between dots. Second focal plane scope is mil-accurate only on one specific magnification and you have to do math if you use other magnifications. I keep a small printed paper with me which contains ranges, magnifications and corresponding clicks/mils to take correct holdover.

I hope this is any help. There probably are ready mildot calculators online, but this is the way I do it :)
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/12/2009 at 08:50
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Edit:
1 mil is 4*3,6" = 14,4"@400 yards.
Corretion:
4 mil is 4*3,6" = 14,4"@400 yards.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/12/2009 at 11:17
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Vortex Dead Hold BDC has nothing to do with Mils and Mil-Dot's

edit to add -  I don't know if Vortex recommends any certain ballistic program and I have never seen one on the site.  You could try to send them an e-mail, they get back to people very quickly and they are extremely nice and helpful.
 
It's probably the best bet to have a larger than normal target with an aiming circle towards the bottom and placed at 50 yards or 100 yards down range....shoot the factory ammunition or already worked-up handloads you have chosen for accuracy and terminal ballistics.  Shoot 3 times for each holding dot on 2 or 3 different powers and make sure you keep a very good log of where they hit.  You can do math from that with any working ballistic program and it'll be more accurate.
 
You could check extensively on just 12x and 8x and then you know 6x and 4x will be double for when you have to dial down.


Edited by danjojoUSMC - November/12/2009 at 11:34
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/12/2009 at 12:05
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Originally posted by Couesfanatic Couesfanatic wrote:

I can't find a way to figure out what the yardages are for my mil-dot reticles are beside burning tons of ammo.
Originally posted by danjojoUSMC danjojoUSMC wrote:

Vortex Dead Hold BDC has nothing to do with Mils and Mil-Dot's
Since Vortex makes scopes with both Mildot and Dead Hold BDC reticles, which one are we talking about here?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/12/2009 at 12:19
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I completely missed that, apologies to you puppezed.  Only saw the Vortex BDC in the thread title.
 
Couesfanatic, JBM seems to be the best free ballistics program online and if you shoot a bullet with the (Litz) designation after it you will be better off.  Those automatically go by the G7 b.c.'s that Bryan Litz also has in his book (you just don't get to see the G7 b.c.'s even though you can figure them out from there).  These are actually tested instead of general manufacturer G1 b.c.'s that are more suited towards round nose, flat base bullets and are computer generated.
 
You should be able to do some easy mil-dot calculations once you figure out you true muzzle velocity, altitude, temperature, etc.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/12/2009 at 14:49
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the scope I have s the Vortex Viper. It is MOA's. Heres the picture of my reticles with distances from the Vortex Website:

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/12/2009 at 15:03
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So am I safe to say that the distance of the first reticle down from the crosshair is 1.5 inches at 100 yards, 3 inches at 200 yards, 4.5 inches at 300, 6 inches at 400 and 7.5 at 500?

The second reticle down from center is 4.5 inches at 100, 9 at 200, 13.5 at 300, 18 at 400, 22.5 at 500.

Now I matched up my ballistics to guesstimate where each is at. I am zeroed at 300 yards. 
here are my ballistics:


with some math I figure im at:

300
375
500
625
750


Am I doing this right?

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/12/2009 at 15:52
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well MOA isn't inches but it is close...for long range shooting you want to be more precise.
 
What bullet are you using for 180 grain with a b.c. of .500?   Most are not going to be that high even though they are advertised as such. 
 
You can have two values show up for drop and wind drift with JBM and a couple of others....do one in inches and one in MILS.....no need to even do the math really.  Just confirm it with real range time and expect the G1 b.c.'s to be off by .010-.050 for your actual drop.  Also the G1 b.c. will inflate the velocity numbers so don't try to use velocity or energy given by it to determine how the bullet will act at those distances on an animal. 
 
Your thinking is right there in the ball park though
 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/12/2009 at 17:03
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I'm using Remington Siccoro power level three bullet. I got that number of Remingtons website here:

http://www.remington.com/products/ammunition/ballistics/results/default.aspx?type=centerfire&cal=38


Wow JBM is awesome.  Excellent
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/12/2009 at 17:08
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Thanks for your help. Can you look this over to make sure I didn't enter anything way off? 


Now I need to go to the range and double check these numbers by actual shooting.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/12/2009 at 17:21
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It's going to be very close bud....you should try to give Mr. Litz an e-mail and see if he can give you a little info on the G7 b.c. for the Scirroco....it will be more accurate.  You need a way to get the right altitude, pressure, etc. for where you are at to be very precise.  You will be in the ball-park though. 
 
Try putting MILS as a measurement column (instead of MOA) to go with the inches column.
 
bryan.litz @ bergerbullets.com just take out the spaces, he is a nice guy and will have 1,000x better advice than me
 
 
 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/12/2009 at 20:26
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You can run the numbers and get eerily close. I have a Zeiss Conquest with a Rapid-Z 600 reticle and on their website they have a program that allows you to match a certain factory load or hand load with the reticle and give you the optimum power setting for 100 yard increments +/- a little. Scope height, temperature, feet above sea level are all calculated into the equation. I have it on a .270 with one bullet my optimum setting is 7.42X and with another it is 7.91X.  I've extrapolated what they have done to dope my Leupold 4X12 with a long range reticle and here is how I did it. Using the factory ballistic chart I was able to establish an estimate for bullet drop. Zeroed at 200 yards the bullet should drop (x) at 300 and (y) at 400. Measured and marked a target accordingly and set it up at 300 and 400 respectively and dialed in the appropriate power, for my .308 a Hornady 168 grain A-Max it was 9.7X on paper and after shooting groups to verify it ended up being 9.5X.
Very little time or ammunition was needed and it is spot on.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/12/2009 at 21:05
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dls56, that is great it was right there with the shooting.  What length of barrel does the rifle have that matched the listed velocity so well?  
 
I like Hornady, I think their new Superformance ammunition will be extremely interesting.
 
 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/23/2009 at 21:37
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Originally posted by puppezed puppezed wrote:

If you know the flight path of the bullet, you calculate the correct holdover. You can get the flight path for the bullet by mapping the flight path yourself by shooting at different distances or calculate it with a ballistics software if you know bullet weigth, bullet ballistic coefficient and initial velocity. For example Norma´s website has a free ballistic software.
www.norma.cc

When you know the flight path, you can calculate how many dots you need to take correct amount of holdover. The distance between dots is 1 milliradian, which is 10cm@100m, which is exatcly 3.6"@100 yards. Now you divide can this 3.6" with 100 yards and multiply it with the desired distance, so you get -> 7.2"@200yards and 10.8"@300yards and so forth.

Let´s say you have zeroed you rifle at 150 yards and the bullet drop is -27.3"@ 400yards. 1 mil is 4*3,6" = 14,4"@400 yards.  27.3/14.4 = 1.9, so correct holdover is 1.9 mil radians. Because the diameter of a dot is usually somewhere between 0.20-0.25mils, depending on a scope, you would have to take aim with top end of the second dot downwards.

Of course you have to keep in mind that Vortex Viper is a second focal plane scope, so adjusting magnification will change the space between dots. Second focal plane scope is mil-accurate only on one specific magnification and you have to do math if you use other magnifications. I keep a small printed paper with me which contains ranges, magnifications and corresponding clicks/mils to take correct holdover.

I hope this is any help. There probably are ready mildot calculators online, but this is the way I do it :)

Flight Path vs. Slope/dope simplified by a range finder but you have to account for gravity pulling the bullet down as it travels. Get base line , velocity/ D cos (angle) muzzle velocity, oal bullet + all environ. cond. etc. many variables differing.


If you wish to calculate the time of flight of your bullet then you need to know the horizontal component of the distance vector (the base line) which is parallel to the earth surface. Time of flight is Velocity/D cos (angle). Get the velocity during flight, you need the muzzle velocity, environmental conditions, shape of the bullet etc. variables known. COS (deg) = hypotenuse / adjacent baseline.


I see some things wrong with the caculations and the use of your milliradians.

 
Radians are unitless measurements which are comparative to degrees.

 

They measure the distance which you have gone around a circle.

 

2 PI radians = 360deg.

 

Using 3.14285714285714

as the value of PI, 2 PI (6.285714285714) radians complete a full circle.

 

Radian just a measurement of rotation.

 

This is the system used in the mil-dot reticle. It is a simple calculation or the degrees / radians.  Most are milliradian .0001 or 1000 radians or 1/1000 radians.

 

This is how we come up with 1 milliradian being more than 3.6in @ 100.

Tangent(.001)(100)(36)=3.6000012 not exactly 3.6" (a little more)

 

The simplest form for the measurement of a target of ~6ft at 1000yrds. 2 milliradians hence the mil-dot reticle dots being spaced in milliradians allowing the shooter to get to the distance of a man by assuming height.  Likewise the assumed height of a target in yards divided by the height of a target in milliradians by 1000 equalling the distance of that target in yards.

 

Target’s head breaks 1 dot and feet break 4 dots down.  (2/4)*1000=~500yrds +-

 
Very simple.


Edited by 338LAPUASLAP - November/23/2009 at 21:41
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Originally posted by 338LAPUASLAP 338LAPUASLAP wrote:

Originally posted by puppezed puppezed wrote:

If you know the flight path of the bullet, you calculate the correct holdover. You can get the flight path for the bullet by mapping the flight path yourself by shooting at different distances or calculate it with a ballistics software if you know bullet weigth, bullet ballistic coefficient and initial velocity. For example Norma´s website has a free ballistic software.
www.norma.cc

When you know the flight path, you can calculate how many dots you need to take correct amount of holdover. The distance between dots is 1 milliradian, which is 10cm@100m, which is exatcly 3.6"@100 yards. Now you divide can this 3.6" with 100 yards and multiply it with the desired distance, so you get -> 7.2"@200yards and 10.8"@300yards and so forth.

Let´s say you have zeroed you rifle at 150 yards and the bullet drop is -27.3"@ 400yards. 1 mil is 4*3,6" = 14,4"@400 yards.  27.3/14.4 = 1.9, so correct holdover is 1.9 mil radians. Because the diameter of a dot is usually somewhere between 0.20-0.25mils, depending on a scope, you would have to take aim with top end of the second dot downwards.

Of course you have to keep in mind that Vortex Viper is a second focal plane scope, so adjusting magnification will change the space between dots. Second focal plane scope is mil-accurate only on one specific magnification and you have to do math if you use other magnifications. I keep a small printed paper with me which contains ranges, magnifications and corresponding clicks/mils to take correct holdover.

I hope this is any help. There probably are ready mildot calculators online, but this is the way I do it :)

Flight Path vs. Slope/dope simplified by a range finder but you have to account for gravity pulling the bullet down as it travels. Get base line , velocity/ D cos (angle) muzzle velocity, oal bullet + all environ. cond. etc. many variables differing.


If you wish to calculate the time of flight of your bullet then you need to know the horizontal component of the distance vector (the base line) which is parallel to the earth surface. Time of flight is Velocity/D cos (angle). Get the velocity during flight, you need the muzzle velocity, environmental conditions, shape of the bullet etc. variables known. COS (deg) = hypotenuse / adjacent baseline.


I see some things wrong with the caculations and the use of your milliradians.

 
Radians are unitless measurements which are comparative to degrees.

 

They measure the distance which you have gone around a circle.

 

2 PI radians = 360deg.

 

Using 3.14285714285714

as the value of PI, 2 PI (6.285714285714) radians complete a full circle.

 

Radian just a measurement of rotation.

 

This is the system used in the mil-dot reticle. It is a simple calculation or the degrees / radians.  Most are milliradian .0001 or 1000 radians or 1/1000 radians.

 

This is how we come up with 1 milliradian being more than 3.6in @ 100.

Tangent(.001)(100)(36)=3.6000012 not exactly 3.6" (a little more)

 

The simplest form for the measurement of a target of ~6ft at 1000yrds. 2 milliradians hence the mil-dot reticle dots being spaced in milliradians allowing the shooter to get to the distance of a man by assuming height.  Likewise the assumed height of a target in yards divided by the height of a target in milliradians by 1000 equalling the distance of that target in yards.

 

Target’s head breaks 1 dot and feet break 4 dots down.  (2/4)*1000=~500yrds +-

 
Very simple.

However, for the purposes of long range shooting (where 1-2MOA is often considered "negligible"), the fact above that 1mil at 100 yards is more than 3.6inches (3.6000012)<
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/27/2009 at 00:41
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Coues--you're getting it right. Remember reticle subtensions are an angular form of measurement, just like u posted before. The critical part of the whole thing is the units. Technically the stadia aren't "inches at 100 yds.", but it's more precise to refer to it as Inch PER hundred yds. (IPHY) The angular concept is hugely important. As Danjo. mentioned earlier MOA is equal to 1.05 IPHY, and won't make a lot of difference till u get to 600-700 yds. or so. It's so close in fact that IPHY is often referred  as Shooter's MOA or SMOA. The angular systems of measurment that u're gonna run into most r--
 
1) milliradian or mil. or mrad. (people like to interchange these terms 'cause it sounds cool).
 
2) minutes of angle or MOA or just minutes
 
3) inch per hundred yds. or IPHY or SMOA
 
If u're getting into this stuff it's probably a good idea to be able to convert quickly between all units too, so
 
1 mil=3.6 IPHY=3.44 MOA=3.6 SMOA
 
and 1 MOA=1.0472 IPHY (1.5 is close enuf. unless u're shooting flies...OR rangefinding with reticles).
 
Another thing to remember is that the magnification of 2nd focal plane variable power scopes is inversely proportional to subtension (another term to remember, BTW). In other words if u have a 6.5-20x mil-dot scope that's calibrated for 10x (fairly common amongst mil-dot scopes), then at 2x the power (20) the subtension becomes 1/2 the measurement (1.8 IPHY). It's usually not perfect but it's close. That's the concept behind the Zeiss Rapid-Z reticle zeroing system. They offer their calcs at the touch of a button (Exbal too, BTW), but all of these can be done with any ballistics program and a calculator.
 


Edited by sscoyote - November/27/2009 at 00:43
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My .308 is 24" with 5R rifling. Sorry for the late response.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/27/2009 at 09:55
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for informational purposes -- the swaro program is set up just a bit different, swaro uses groups of trajectorys, the same way as leopold does in their bas system. so in the swaro method, with a 200 yd, zero, all you need to know is your drop between 200 and 300 yds, to use their reticle, which also works in reverse to be used as a ranging reticle. Leopold uses the same method except you read the range off the power dial. both methods decrease the magnification to raise the poi for those calibers that don't shoot as flat. for your reticle print one round at 100 yds using the each of the hold overs as dead center and measure the distance with a tape between the holes. this gives the moa hold over at 100 (and its conversions for any distance).
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from your picture the 11 moa marking -- is just that ----11 moa from a zero center at 100 yds, with your rifle and a 175 gr smk, using the 11 moa holdoverit will strike about 2 inchs high at 500 yds, but be on a 8x10 piece of steel every time with a 5" cone of fire.
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dial in trajectory compensation methods of target hold use a different philosophy than hold reticle hold over methods. the distance calculation is made (ignoring the 5% error as the distance increases for a moment) and assuming the distance is correct the drop is dialed in-- but the hold is still center of mass--- bullet drop reticles do not always use center of mass holds because the distance never comes out in whole integers (100 yds, 300 yds) etc. -- so a 327 yd shot requires some interpolation as to where to hold. (assuming the correction is not dialed in, which is an option)
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