Bullet drop to mil confusion

[WEBSTER113]

1 MIL @ 100 yards = 3.6"
1 MIL @ 1000 yards = 36"

At 1000 yards, Ballistics AE shows my bullet to have 419.5" of bullet drop with a correction in MILS of 11.9
Here is my questions: 11.9 MILS X 36 = 428.40" or a miss high by 8.9".

If I put the exact same data in Bryan Litz, Applied Ballistics I get a bullet drop of 418.9" with a correction of MILS of 11.64 which is true to the 36" at 1000. I also put it in JBM and it also holds true to the 36" at 1000

Why do I have a .3 MIL difference between them and how do I go about getting Ballistic AE to follow the rule?

What am I missing?

 

[WEBSTER113]

So I think I am getting closer, but could use some input.
My personal Ballistics AE has an addition +/- 2.1% added to the overall MIL correction.

Help me walk through this:

1000 yards = 36" per MIL

My 1000 yard shot calls for the 419.5" drop and a MIL correction of 11.9.
Actual Mil correction for 419.5" drop would be 11.6"
(419.5" / 36" = 11.65 (same as Bryan Litz & JBM)

However, Ballistics AE is calling for a 11.9 MIL drop which would be 35.252" per MIL
(419.5" / 11.9 = 35.252")
To confirm this: 419.5" / 35.252" = 11.9

If you take the 11.9 and multiply it by the true 36" per MIL at 1000 yards, you would have a bullet drop of 428.4"
To confirm this: 11.9 x 36" = 428.4"

So to confirm that there is indeed a 2.1% error I did:
428.4" / 419.5" = 1.021 or 2.1%
also,
11.65 x 1.021(2.1%) = 11.89(rounded to 11.9)

I have done this same thing for 400, 600, and 800 yards and came up with the same error.

So why would I / Ballistic AE have an error of +/- 2.1% in the MIL correction?

 

[WEBSTER113]

All right every body, I really could use some input on this one.
I have tried every which way from changing out the atmospherics, sight height, zeros, played around in the "settings", deleted the entire APP and completely started over, and compared it to two others using AE and they show the same thing.

Why cant I get the bullet drop to equal 1 MIL = 3.6"?

 

[DKDravis]

I have just checked my two versions of Ballistic (Ipad and AE) both of them show no error on the inch / Mil conversions...

Very strange indeed ...

 

[wigwamitus]

Maybe I'm missing something, but have you recorded you "zero" range in the AE program?

 

[WEBSTER113]

Wigwamitus, I have recorded my zero range and I have tried that every which way.
Can someone please try what I have show and let me know what they come up with?

Litz Ballistic Coefficient: .308 Sierra 175gr HPBT MK 0.243
Bullet Diammeter: 0.308
Bullet Weight: 175gr
Native Drag: G7
Muzzle Velocity: 2552
Chrono: 10ft
Use Drag Model: G7
Zero Range: 100 Yards
Sight Height: 2.14"
Cant Angle: 0
Zero Atmosphere: DA: 6350, Mach: 63.4
Wing COnfiguration: No wind
Maximum Range: 1000yards
Minimum Range: 500
Range Increments: 100
Vital Zone: 5
Elevation Turret: mRad
Windage Turret: mRad
Spin Stability: OFF
Coriolis: OFF

Calculate, at 1000 yards I show 1000 yards at 384.0" with MIL correction of 10.9 which should show 10.66

 

[wigwamitus]

Well if DKDravis isn't seeing the error in his version of Ballistic AE, then maybe Webster113 should try the email support on the Ballistic AE page.

 

[wigwamitus]

Your arithmetic looks correct to my eyes. And your localization process seems strong as well (deleting the app and starting over). So at least in parallel, try the AE email support path.

 

[WEBSTER113]

I have sent emails off to the support and haven't heard back.

 

[WEBSTER113]

I am wondering if I did something in my settings to cause this.
Although I have been going back and forth on everything I can in them and nothing seems to change the output.

Can someone please maybe run through there settings on the more important things and let me know what they are using.

 

[wigwamitus]

I use the AB program for droid, so not relevant, but maybe DKDravis will try to replicate for you and show his work .

I had a problem with my AB being off and it was my "sight height" ... and someone here was able to point it out for me, so I believe you will get it solved ... but might take more than 5m more .

 

[WEBSTER113]

I use the AB program for droid, so not relevant, but maybe DKDravis will try to replicate for you and show his work .

I had a problem with my AB being off and it was my "sight height" ... and someone here was able to point it out for me, so I believe you will get it solved ... but might take more than 5m more .

I just tried playing with the sight height and returned it back to the 1.5 vs. the 2.14 and that didn't work.
I also just started from scratch again this morning and still have the error.

 

[WEBSTER113]

If I switch the outputs from MRAD to MOA than the math works out showing 36.67MOA (384/10.47=36.67)
But once I switch it back to MRAD I have the same problem.

 

[wigwamitus]

Well perhaps you at least have a work around until you can get the MRAD solution!

 

[WEBSTER113]

wigwamitus, can you please check in your settings on what you show your MIL-DOT Specs at? USMC or ARMY
I have been running ARMY and getting the wrong output, but if I switch it to USMC it appears to work!

 

[wigwamitus]

That is hilarious ... program must have been written by a USMC guy !!!
ARMY=WRONG
USMC=RIGHT

I'm keying your data into AB, will post results shortly.

 

[wigwamitus]

Questions:

What is that .243 number?

Litz Ballistic Coefficient: .308 Sierra 175gr HPBT MK 0.243

I'm using 1.24 for bullet length

What BC are you using? I have .485

 

[Lowlight]

The Army Mil was only used in one scope and it used the rounded, "military mil" of 6400... it was just on the M3A, no other scope had this issue.

So that is probably why, when the USMC came out with the MST-100 with mils, a few short years later the Army wanted a Mil Dot scope and contracted Leupold. They thought the USMC did it wrong because the mils used in Artillery and the spacing used with the lensatic compass. (also a military mil) So they designed the scope with that in mind. Immediately it was pointed out the Artillery unit was a rounded version of the true mil number.

Then people mistakenly thought it was the difference between the round mil dot and the oval mil dot, so they started using the Army Mil vs USMC mil, but key point was center to center. With the Army using 6400 instead of 6283 that changed it making it off. Today everything is the same center to center and uses the same number the USMC did from the beginning.

Initially it was thought the USMC was incorrect but it was the Army that messed it up.

 

[wigwamitus]

Excellent !!!

 

[WEBSTER113]

Lowlight, where were you two nights ago when I was loosing sleep over this!

Thank you everyone for you help!

 

[ahhshoot]

Sucks you can't use the program as it's designed. It sounds like a programming issue. I typically just look up my drop and divide it by 3.6 on my cellphone calculator. If the drop in inches is correct then the mil adjustments are, too.

Edit; just read lowlight's comment, good stuff. Thanks for the insight everyone, I have learned something new today.

 

[Blowby]

Same error on my AE. Went to setup and changed to USMC and all is good!
Thanks for pointing this out.

 

[WEBSTER113]

Questions:

What is that .243 number? I'm using 1.24 for bullet length

What BC are you using? I have .485

The .243 is Bryan Litz G7 BC.

 

[wigwamitus]

ok, I'm changing all my 175gr data to g7 .243 ... thx!

 

[DKDravis]

I only just got back to this thread...

I copied all of your setup... I still had no error, so I assumed that there was a bug in your version of "Ballistic".. Never thought of the USMC vs. ARMY Mil problem.

Here in DK we get messed up a lot with that, because all our artillery devices use the 6400 "mil" system.. But since I only ever use it with my scopes, I very rarely change that setting in my ballistics software.

 

[Ring]

All right every body, I really could use some input on this one.
I have tried every which way from changing out the atmospherics, sight height, zeros, played around in the "settings", deleted the entire APP and completely started over, and compared it to two others using AE and they show the same thing.

Why cant I get the bullet drop to equal 1 MIL = 3.6"?

"My personal Ballistics AE has an addition +/- 2.1% added to the overall MIL correction."

u answered your own question...

most likely u have you "elevation turret" value set to something other then 1.000 on the trajectory screen, and in your favorite...

 

[brianf]

"With the Army using 6400 instead of 6283 that changed it making it off"

just like the US army rounding to 6400 to make the math easier the russians (at least they used to) round it to 6000 to even simplify it more. most of their scopes issued at the time did not have mil dots they used a ranging ret like the old leatherwoods ans such. I think it is Norway or the sweedish that actually use 6200 as well, to each their own i guess.

 

[Aimsmall55]

Just for future reference.... If you've got an IPhone , go to settings on the actual phone itself. Hit on Ballistic AE towards the bottom in Apps. You've got a "mil dot spec". Click on it and you can change from army to USMC. Also on your angular unit change from moa to mildot

 

[runningun6mm]

I had heard Lowlight's explanation a long time ago... Dad did some time as artillery gunner in the army. And of course I did four years USMC... so when given the option on army mil vs usmc mil... i dumb luck guessed the usmc mil option... but then again I'm using the Shooter app.

 

[Ring]

BTW, USMC is the program default, so if it was set to army, it was something you did

 

[WEBSTER113]

BTW, USMC is the program default, so if it was set to army, it was something you did

It most certainly was something that I did in my AE settings.
I made the change in the settings so that the MIL dots in my scope would match the same as the MIL dots used in the AE APP. (apparently other were/are doing the same thing)
Until now, I was under the impression that ARMY MIL dots were round and USMC MIL dots were more oval shaped, all of which would have followed the same 1" at 1000 equal 36".
I had no idea about the artillery reason or history behind it all.

I personally noticed one night that the math wasn't adding up and was looking for help/advice as to why.

 

[Notso]

What I don't get in this whole thread is why any of you are even concerned with how many inches the bullet drop is at 1000 yds. Why does it matter??? All that matters is that your bullet drop is 11.9 mils or whatever it is. If one ballistic program says its 11.9 and the other says its 11.64, then there is a discrepancy somewhere - but I just don't get this fascination with the constant need to convert mils to inches and back. If you miss high (in the OP example), you miss miss high by .3 mils. Who cares how many inches, centimeters, kelvans, jellybeans or whatever it is? A mil is a mil.

 

[CampingJosh]

If you miss high (in the OP example), you miss miss high by .3 mils. Who cares how many inches, centimeters, kelvans, jellybeans or whatever it is? A mil is a mil.

See, that's the problem he just discovered: a mil is not necessarily a mil. There are apparently at least 4 different measurements for what mil is depending on which system is in use. (I didn't know about any of this until reading this thread.)

Had the OP never bothered to look at the math, he would have simply thought that he was shooting poorly when he was missing high by .3 mils. ("Poorly" here is obviously very subjective.) He would never have learned that the mils in his scope did not match the mils as he has his program set.

Besides, it's much easier to calculate bullet drop as a linear measurement (inches or such) than as an angular measurement.
Actually... I'm not sure how to calculate bullet drop at a given distance directly as an angular measurement without first calculating the linear distance. Some math genius could perhaps do it, but I have't taken a math class for 10 years.

 

[TacticalBoltKnob]

See, that's the problem he just discovered: a mil is not necessarily a mil. There are apparently at least 4 different measurements for what mil is depending on which system is in use. (I didn't know about any of this until reading this thread.)

Had the OP never bothered to look at the math, he would have simply thought that he was shooting poorly when he was missing high by .3 mils. ("Poorly" here is obviously very subjective.) He would never have learned that the mils in his scope did not match the mils as he has his program set.

Besides, it's much easier to calculate bullet drop as a linear measurement (inches or such) than as an angular measurement.
Actually... I'm not sure how to calculate bullet drop at a given distance directly as an angular measurement without first calculating the linear distance. Some math genius could perhaps do it, but I have't taken a math class for 10 years.

You may not have taken a math class in 10 years, but your logic is impeccable.

 

[M40_A1]

A mil is a mil.

As we just learned (or were reminded), boys and girls, an inch is an inch (as in always).

 

[Johan L.]

"With the Army using 6400 instead of 6283 that changed it making it off"

just like the US army rounding to 6400 to make the math easier the russians (at least they used to) round it to 6000 to even simplify it more. most of their scopes issued at the time did not have mil dots they used a ranging ret like the old leatherwoods ans such. I think it is Norway or the sweedish that actually use 6200 as well, to each their own i guess.

Russia and Finland: 6000
Sweden: 6300 before 2007 but now we use mils in Sweden, i.e. 6400.

 

[brianf]

learn new something everyday, thanks. only took 100 years but at least all the guys on the same team use the same info.

 

[Johan L.]

You never know. Maybe someday we all use the correct number 6283...

 

[Luky]

Interesting thread. I use Strelok Pro with a Vortex PST 6-24x56 ffp mil/mil scope and have noticed actual adjustment is off by 2 to 3 clicks (.1 mil clicks) from the program when I get past 600m or so (on my dope card). I'll have to dig into this a bit more... Anyone know what Vortex uses for mils? 6000, 6200, 6283, 6400?