Drop in Inches and Windage in Inches

[Loaded247]

Hey guys I was just hopping someone would be able to shed some light on, drop in inches and windage in inches, via mil dot style scopes. I have a general understanding of the formulas and how to apply them. My biggest problem is trying to understand where the drop in inches and windage in inches, variables come from. I always see other shooter plugging them into their equation to get their holdovers but i don't know how they got them. If anyone would be willing to explain how to get those two variables I'd really appreciate it. Thanks!

 

[40xs]

I don't think in terms of drop, I figure in terms of come-ups based on bullet strikes. If I knew what bullet you are using and your muzzle velocity I may be able to get you in the "black" or close to it from 100yd out to 1000yds.. Your B.C will give you a reasonable windage adjustment If you know the approx. wind speed and or value ( based on angle of wind). I just started using the new 185 Berger juggernaut and only know the come-ups for 1k yds. But my old 185 vld. in .308 is 3.5 @ 300, 14moa @600and 33 moa @ 1k. ( depending on temperature at the time). Since you know the math on converting moa to mils you should be able to cross ref. I hope this sheds a little light on your question.

 

[Sterling Shooter]

Being able to convert inches to MOA or MOA to inches is about a heartbeat's worth of math, and may be helpful for a quick hit. For example, which is easier to understand: let's say a 600 yard wind reading suggests a favor of 6 MOA. Now, assume you are using iron sights, would you be able to favor having info only in MOA? No, because you don't understand what 6 MOA looks like at 600 yards. Instead, you would click on the necessary adjustment without conversion, but, with about 24 clicks, assuming a 1/4 minute sight, you might need more time than you've got to hit the target. Why not Just mulitply 6 X 6, knowing 1 MOA is about 6 inches at 600 yards. This will provide recognition of a 36 inch favor, which is much faster than clicking.

 

[Loaded247]

Ok I'm using a Savage 110 BA .338 Lapua Magnum with a Nightforce NXS scope with the NPR1 (which I believe is a MOA style) reticle. I'm not 100% sure on the magnification, its either the 8-32x56 or the 12-42x56.
I do not currently have a ballistic calculator, I wasn't aware of its importance until recently. I do plan on getting one. The formulas I am refering to are ( inches of drop or /windage ÷ inches value of 1 mil at given range). Now that I look at it the formula wouldn't even apply to me since I am using MOA instead of MILs.
You know guys ive studied so much and looked at so many different things on long range shooting that I don't even know what's right anymore. Personally I would rather just start over with something solid. If anyone has any recomendations to any kind of book or video that has solid information and is fairly easy to understand I would appreciate it. I know that a lot of people talk about the USMC Sniper Manual or Accuracy and Precision for long range Shooting by Bryan Litz, if those are helpful ill go get them right now.
I do apologize I'm not trying to bash anyones advice. I do appreciate all of it, I'm just struggling to understand because I think ive only picked up bits and pieces of this sport that may or may not be wrong and I'm having trouble connecting what I know to what other shooters are trying to explain to me. Again I apologize and if anyone has any solid sources to go to I would really appreciate it.

 

[Lowlight]

It's not a good idea to think in inches with a scope, if you are using Iron Sights, have at it... you have no other choice, but scopes... bad choice.

To figure out MOA from Inches you use the following

Inches X 100 / 1.047 x Distance = MOA

To Convert MOA to Mils you divide the MOA by 3.43 to get the mil equivalent

The problem with Inches and what not, you have to then rely on distance where if you use TMOA or Mils you can ignore the distance and use the observed value. (providing your scope's reticle matches it turrets). Then 1 Mil observed from center is 1 Mil on the turret at any distance. Same with Matching MOA or IPHY scopes, 1 MOA observed is 1 MOA regardless of the distance. There is no multiplication.

Going to a ballistic Program like JBM Online which is FREE, you can tell the software to output your data in 2 units of your choice. You can mix and match to your hearts' desire.

Finally, if you have a Mil reticle and MOA turrets, it's best to use 1 MOA adjustment per .25 Mils observed in the reticle. (using the reticle like a ruler) So for every 1 Mil Dot you see you a have 4 MOA of adjustment. You can divide the distance between the dots into quarters, so .25 = 1MOA, .5 Mils = 2 MOA, .75 Mils = 3 MOA, etc.

All of this should be done before you leave the house, it's 2013, no form of any math should be done on the line. We can print data sheets, ranging charts, etc all before we leave. Then you just use the charts to determine your adjustment. No thinking, just reading... it's easier, simpler, etc. JBM is an awesome resource that can not only get you on target but teach you how to use these units to you advantage. Just because Iron Sight guys did "X" in 1978, doesn't mean we have to do it now. And trust me there formulas for wind and what not are absolutely incorrect for a 338LM, they were written for a 308 shooting a 168 and happen to work in a passable manner for a 5.56 out to 600 yards, but for anything else they are wrong. And people wonder why the wind is so wicked, they are using bad data that was barely valid 40 years because nobody bothers to run the formula for the correct constants. (yes there are other formulas)

Good luck... think Minutes or Mils, not inches... Unless you are using a scope that adjusts in IPHY then you can use inches.

 

[Graham]

...would you be able to favor having info only in MOA? No, because you don't understand what 6 MOA looks like at 600 yards. Instead, you would click on the necessary adjustment without conversion, but, with about 24 clicks, assuming a 1/4 minute sight, you might need more time than you've got to hit the target. Why not Just mulitply 6 X 6, knowing 1 MOA is about 6 inches at 600 yards. This will provide recognition of a 36 inch favor, which is much faster than clicking.

Myth.

No one is talking about iron sights. And no one is favoring anything to hit something.

But even if we were talking about irons you can't objectively determine 36" at 600 yards without a known distance and a known target size, and even then you just think you can.

 

[Sterling Shooter]

Your statement is as inaccurate as your knowledge about the subject. If I can favor a target, I will already know the size of the target and target distance. You really should move on to something other than following my threads to play gottcha. Maybe learn how to shoot. Your statement that no one is favoring anything to hit something is absurd. Favoring with irons or with scope is an appropriate method of countering wind when clicking is not possible or appropriate, such as when using an AGOG.

 

[mrbungle]

thanks for that post , lowlight. simple and easy to understand.

 

[Graham]

Your statement is as inaccurate as your knowledge about the subject.... You really should move on to something other than following my threads to play gottcha. Maybe learn how to shoot.

Don't flatter yourself: I'm not following you around. I am simply correcting bad information when I see it. And this one had your name on it.

If I can favor a target, I will already know the size of the target and target distance.

Precisely. That's what I said, and one reason why the information in your post is bogus.

Favoring with irons or with scope is an appropriate method of countering wind when clicking is not possible or appropriate, such as when using an AGOG.

Hmmm.... Decanting a wine is an appropriate method of letting it breathe when reducing the amount of sediment is not possible or appropriate, such as when serving a bottle that was stored on its side.

The OP asked a question about 'mil dot style scopes' and asked how to apply holdover formulas. You posted a reply about iron sights and told him to 'favor' in inches. That's an incorrect technique for using a mil dot scope. When you re-post the same information again and again it can be helpful, like your 1980s-vintage marksmanship fundamentals posts for example, but not when it doesn't answer the question being asked.

BTW, and again in yet another reply to your attacks on my shooting ability, I am prepared to publicly admit that you are probably a better shooter than I am - especially if it will stop you from repeating that information as well. But I would prefer that you come out to one of the major matches and test your skills in person. Perhaps I can convince Frank to offer you an incentive to show up at the Sniper's Hide Cup next year. And if you decide to come, don't favor in inches.

 

[Sterling Shooter]

Bad information, no, just more detail on the subject in general and the reasoning behind it so that folks don't remain like you, not knowing that they don't know. My example of ACOG usage highlights it. Having a broad knowledge base to be able to properly counter for the effects on trajectory no matter what sighting device is secured to the rifle is paramount to becoming an accomplished marksman. And, after all, this thread is in the Basic Marksmanship section so I don't believe my contribution to the OP's breath of understanding about the concept is out of bounds, unless you're making the rules here. And why would you want to keep someone in the dark? Why not help the novice shooter fully understand the subject matter. What I think is going on here is that you do not have much experience with marksmanship and can only mimic your gurus on matter. This always gets you in trouble. You need to learn it yourself before you profess it. The bottom-line is that there are many posts here from novice shooters seeking direction. These folks could be given a sparse map, but why not give them a more complete map, that's to say, one greater than what they believe they need, thus assuring a better opportunity not to miss any landmarks that could help them reach their destination.

 

[Graham]

...Or we could help the new people by answering their questions.

Bad information, no, just more detail on the subject in general and the reasoning behind it so that folks don't remain like you, not knowing that they don't know... And, after all, this thread is in the Basic Marksmanship section so I don't believe my contribution to the OP's breath of understanding about the concept is out of bounds, unless you're making the rules here.

I think that you have knowledge of the fundamentals of marksmanship. And I agree with you that knowledge is important. But knowing when that knowledge is relevant, and being able to apply it, is more important for an instructor.... As is knowing one's limitations.

What I think is going on here is that you do not have much experience with marksmanship and can only mimic your gurus on matter. This always gets you in trouble. You need to learn it yourself before you profess it.

'I know you are but what am I' was never a successful argument on the playground; it is even less successful among grownups.

I remember the 80's. I was there. I remember NRA high power shooting, M14s, jackets and slings and irons, and I remember reciting the fundamentals after viewing the slide show. I trained on a Lee Enfield and a Parker Hale. It was a wonderful time in the history of the development of marksmanship. Much of that is still relevant today. But much of it is not, because the world didn't stop there.

 

[Gunfighting Inc]

These folks could be given a sparse map, but why not give them a more complete map, that's to say, one greater than what they believe they need, thus assuring a better opportunity not to miss any landmarks that could help them reach their destination.

While the idea of giving a novice a full dowsing of information on a subject may seem like one is providing a valuable and selfless service, it is often not intended as a service at all, but rather a selfish and shallow attempt to show an enthusiastic audience how smart one thinks he is. Knowledge runs vertical. Line upon line, precept upon precept. As we learn a concept we become ready for the next. To expose one to a concept before a foundation of knowledge and understanding makes one ready for it is to do a disservice to the student. Using your map analogy, it is the wise and valuable teacher who has the confidence, ability and patience to give his student a map that will ensure successfully reaching the goal. It is the selfish showman who gives the student a map with so many paths the poor student wanders around until frustrated, never getting anywhere.

 

[Sterling Shooter]

While the idea of giving a novice a full dowsing of information on a subject may seem like one is providing a valuable and selfless service, it is often not intended as a service at all, but rather a selfish and shallow attempt to show an enthusiastic audience how smart one thinks he is. Knowledge runs vertical. Line upon line, precept upon precept. As we learn a concept we become ready for the next. To expose one to a concept before a foundation of knowledge and understanding makes one ready for it is to do a disservice to the student. Using your map analogy, it is the wise and valuable teacher who has the confidence, ability and patience to give his student a map that will ensure successfully reaching the goal. It is the selfish showman who gives the student a map with so many paths the poor student wanders around until frustrated, never getting anywhere.

Unless you hold a teaching degree, I'll take your teaching strategy as uninformed opinion. I actually have a minor in teaching, so I know a little bit about the topic of learning and teaching methods. It prompted my original post. You might want to read it. The gist of it is that since the OP was soliciting information about " windage in inches", why not explain a context for when conversion of MOA to inches is indeed relevant. Remember, learning always begins from the student's perspective.

 

[thrusty]

Derailed....but good read nonetheless.

 

[Gunfighting Inc]

Unless you hold a teaching degree, I'll take your teaching strategy as uninformed opinion. I actually have a minor in teaching, so I know a little bit about the topic of learning and teaching methods. It prompted my original post. You might want to read it. The gist of it is that since the OP was soliciting information about " windage in inches", why not explain a context for when conversion of MOA to inches is indeed relevant. Remember, learning always begins from the student's perspective.

And thus we see another classic example of the self serving thinker: He immediately dismisses any idea not supported by his own experience as uniformed opinion; and, while stating that learning begins from the student's perspective, seems more intent on advertising and defending his own.

 

[Lowlight]

Today at my Precision Rifle Class for T3 Training in Longmont we had Old School meets new...

We shot this rifle, out to 1000 yards, in fact it was pretty much the only rifle one student used. His only other rifle a 1936 bolt action with a 2.5x Zeiss Scope circa WWI.

The initial Dope for the Sharps was determined via ipad Ballistic Calculator on the line, and corrections on target were called using a Zeiss Spotter 60 with Mil Reticle. Difficult wind, small targets, and some outstanding shooting. Inches were converted from Mils on the fly.

We fired over 60 shots using the Sharps rifle. As observed in this image, every student is given a Trimble Recon w/ Horus ATRAG installed, all were taught to use the software as part of a basic class. We also taught them to make adjustments using the ruler in their scope... the success rate, very high, the fun factor for the student who are not inundated with endless math, off the charts. Guys who never shot beyond 500 yards were making first round hits at distance, including 1150 yards, as well the number of second round hits in 14MPH winds were even higher thanks to focused lessons with proven techniques.

Sure the power point slides include the "formulas" and the long hand math to convert using 1960s tech, but the practical application was done using modern tech. The results spoke for themselves.

 

[PowerLine]

The NightForce NPR-1 is an MOA based reticle and almost definitely comes with MOA turrets on it. So ignore inches and mils for now and just get comfortable with MOA. If you go on NightForce's website, you can find what magnification your MOA reticle is calibrated for. Most likely, it's the highest power.

When you start working with ballistic calculators such as JBM, Applied Ballistics for Android, Shooter (I believe IPhone and Android), Horus Vision A-Trag, etc., you will need the following information to get good data back out: The conditions you will be shooting at (temperature, barometric pressure, and altitude will be important) [You can get temp and barometric pressure from the weather station and altitude from a map]; an accurate muzzle velocity for your ammunition, and an accurate ballistic co-efficient (B.C.) for that ammunition. That should get you close. The better programs will then allow you to "true" the data to more precisely fit your weapon system.

As for sources of info: I found Magpul Dynamic's Art of the Precision Rifle to be extremely good information. However, they deal entirely in Mils there.

Feel free to P.M. me if you have any more specific questions. I have a NightForce NXS 5.5-22x56, so I'm very familiar with using MOA. Most of the guys here use Mils as that's more of the military standard.

 

[relentless1]

Lowlight, I am wondering if your measuring with the retical, mils or moa, if it matters whether one has a frirst or second focal plane scope? DOES THIS FORM OF RETICAL MEASURING WORK AT ANY DISTANCE AND ANY FOCAL PLANE SCOPE.. ?

 

[Lowlight]

I use a reticle all the time, I can work in both Mils or MOA, Front Focal Plane just means it is correct at any distance, Second Focal Plane means it has to be established what distances work with the reticle being used.

But the reticle, either Mils or MOA is a ruler and it is placed 6 inches in front of your nose, so why not use it. Yes it works no matter what, it's an angularly calibrated ruler with an optically enhanced system supporting it so you can see better at farther distances.

 

[relentless1]

Thankyou, but to be clearer to me, can you please explain how to exactly do that with a 2 nd focal plane scope?
For instance...if I want to hold off 1 moa at 600 yards, I know that 1 moa is 6 inches, but if I use the moa, s on my retical, heing 2nd focal plane, how do I hold using the 1 moa hash marks...hold over 1 for every 6 inchs of impact I may want??

 

[Lowlight]

They still work, they just work on only 1 magnification, and not all.

If you have a NF 5-22x with an MOA reticle, you just have to hold with the magnification on 22x, then hold your 1 MOA like any other scope.

 

[jolofree]

Don't sweat the inches, forget them. Go to the JBM web site, like LL said, input your own particulars ie bullet, weight, velocity, BC, temp, pressure, etc etc and when you get to it,
select MOA to use with your "Nightforce NXS scope with the NPR1 (which I believe is a MOA style)" to make a range data card for those specific conditions.
Then just dial the dope directly onto your scope from the range card you produced (assuming you have a good 100yd zero) or hold off the
amount indicated by 'reading' your reticle, or dial on your come-ups and hold off reading the reticle for wind, and/or then you can make corrections by observing your misses and adjusting by using the reticle as a measuring stick to make/dial adjustments or hold off the needed amount. ie you fire a shot at an unmarked white steel target (even if you don't know the distance to the target) that you observe thru the scope as it strikes the target right (or left) of center (your POA) and looking thru your scope you use the reticle to 'measure' the distance from the splash mark on the target where the bullet actually struck to the center (POA)
and as accurately as you can be, you determine it to be 1.5MOA out, now either adjust your windage knob on the scope 1.5MOA in the correct direction or hold off your POA 1.5MOA using the reticle in the correct (into the wind) assuming your "call" was good, and fire again, the next shot should be an X if you did your part. ONE Most Important Factor to remember if your scope is second focal plane then it Must be set on the correct magnification 'power' for this to work correctly. It's good to check it on a 'barber pole'. FFP it will work on any magnification. Or check the operator's manual. You can figure it out at other magnification but it gets kinda complicated for a inexperienced shooter. Get used to thinking in MOA or MILs not inches and make your scope match-reticle to adjustments, MOA-MOA or MIL-MIL. See the JBM chart below, it didn't 'paste' right but you get the idea.

Trajectory (Simplified)
Input Data
Manufacturer: Sierra Description: HPBT MatchKing™
Caliber: 0.338 in Weight: 300.0 gr
Ballistic Coefficients: 0.750 [0-1800], 0.760 [1800-2300], 0.768 [2300-5000] G1 (ASM)

Muzzle Velocity: 3250.0 ft/s

Sight Height: 1.70 in Line Of Sight Angle: 0.0 deg
Cant Angle: 0.0 deg

Wind Speed: 10.0 mph Target Speed: 10.0 mph

Temperature: 75.0 °F Pressure: 29.92 in Hg
Humidity: 60 % Altitude: 4500.0 ft

Std. Atmosphere at Altitude: No Pressure is Corrected: Yes
Zero at Max. Point Blank Range: No Target Relative Drops: Yes
Column 1 Units: 1.00 MOA Column 2 Units: 1.00 MOA
Round Output to Whole Numbers: No
Output Data
Elevation: 3.232 MOA Windage: 0.000 MOA

Atmospheric Density: 0.06239 lb/ft³ Speed of Sound: 1133.6 ft/s

Maximum PBR: 417 yd Maximum PBR Zero: 352 yd
Range of Maximum Height: 193 yd Energy at Maximum PBR: 5219.0 ft•lbs

Sectional Density: 0.375 lb/in²
Calculated Table
Range Drop Drop Windage Windage Velocity Mach Energy Time Lead Lead
(yd) (MOA) (MOA) (MOA) (MOA) (ft/s) (none) (ft•lbs) (s) (MOA) (MOA)
0 *** *** *** *** 3250.0 2.867 7034.9 0.000 *** ***
100 -0.0 -0.0 0.3 0.3 3137.6 2.768 6556.5 0.094 15.8 15.8
200 -0.9 -0.9 0.6 0.6 3028.0 2.671 6106.5 0.191 16.1 16.1
300 -2.4 -2.4 0.9 0.9 2921.1 2.577 5683.1 0.292 16.4 16.4
400 -4.1 -4.1 1.2 1.2 2816.8 2.485 5284.4 0.397 16.7 16.7
500 -6.0 -6.0 1.5 1.5 2714.9 2.395 4909.0 0.505 17.0 17.0
600 -8.0 -8.0 1.8 1.8 2615.3 2.307 4555.3 0.618 17.3 17.3
700 -10.1 -10.1 2.1 2.1 2517.8 2.221 4222.0 0.735 17.6 17.6
800 -12.3 -12.3 2.5 2.5 2422.4 2.137 3908.2 0.856 18.0 18.0
900 -14.7 -14.7 2.8 2.8 2329.1 2.055 3612.8 0.983 18.3 18.3
1000 -17.2 -17.2 3.2 3.2 2237.1 1.973 3333.1 1.114 18.7 18.7

14/08/13 22:31, JBM/jbmtraj_simp-5.1.cgi

 

[bogeybrown]

Since JBM has been mentioned a few times here, does someone have a thread link explaining how to use JBM?
I have a couple of "field" programs, but am trying to use JBM in the way LL described to pre-generate dope cards, etc and some of the tech/user interface on the site is kicking my ass.
Thanks

 

[proneshooter]

This is classic.....spending thousands of dollars on gear with absolutely no clue how to use it. Then coming here and expecting to fill his huge knowledge hole in an internet thread.

There is a TON of knowledge in this forum, but it is virtually impossible to impart it to someone like the OP who has absolutely no earthly idea about the concepts being explained to him.

OP, you are well advised to seek professional marksmanship instruction. You need to sit down face to face with someone who can explain to you the very fundamentals of rifle fire control, which at the moment you clearly lack. Without the basic understanding of the angular relationships to control precision rifle fire, nothing we try to tell you here is going to stick.

Sorry. I know that's not what you want to hear, but it is what you need to hear.