Long Range Question...Pretty Basic

[tatasta]

Ok, I have shot quite a bit of medium range rifle (350-500 yds), generally just using typical holdover. I have a Savage 308 LE with a ballistically matched Leupold VX-3. It is great since I just dial it to 700 and that is where it hits.

Subsequently, it does not teach you much about ballistic calculation. So, now, I have a great Mod 70 in 300 Win Mag. with a VX-3 with CDS elevation dial.

Question is:

At 700 yards, my 168 gr bullet will drop 96 inches. My chart shows to come up 52 clicks, which obiously is around 13 inches. So, I can't get my head around how I cover 96 inches with adjustments of only 13 inches/moa.

Maybe I should just bet a custom turret engraved...haha

Thanks

 

[9teenEleven]

Maybe I am off, but isn't it just 7(one for evey hundred) times 13? 91

 

[chaser_2332]

7x1.047+=7.329x13=95.277. So 52 clicks equals 13 moa and at 700 yards equals 95.277"

 

[Uncle Mike]

What is your scopes adjustment value? .250"@100y?

If your reticle moves .250" at 100y, then at 700y, one 'click' will move your reticle 1.750"

52 'clicks' at the 700y value(1.750") would equal 91".

1.750"(your scopes adjustment value at 700y) X 52(Clicks) = 91" of point of impact movement at 700y.

Again.....

.250" (your scopes adj. value at 100y) X 7 (for 700y) = 1.750" (the amount your reticle will move the point of impact at 700y, per click)

1.750" (the amount your reticle moves, per click at 700y) X 52 (clicks) = 91" (the amount of point of impact movement on target, at 700y)

Easy... .250" X 7 = 1.750" X 52 clicks = 91"



To find the amount of clicks you need..... 91" (the amount your bullet drops at 700y) / 1.750" (the amount your reticle moves at 700y) = 52 clicks needed!

91" / 1.750" = 52 clicks needed!

Have fun!

 

[MinnMooney]

Here's one more calculation that most people don't even think about :

There are very few scopes that are accurately calibrated as per "clicks".
I calibrate every scope I get by clamping the rifle with the mounted scope lightly in a padded vise. A surveyor's rod is positioned 50 yards away (or 25, 33.3 or 100) and I start at the mid point of my elevation adjustment range and record the rod reading. Then I'll rotate the elevation knob by 1/2 or full rotations and record the rod readings again. I do that all the way to the "Up" limit and all the way to the "Down" limit. Then I figure what the error is in both MOA and inches. The only error calculation that I print on my stock's "cheat sheet" placard is the MOA error - & I don't care that the knob says, "1/4" @100yds." because scope turrets rarely are close enough to decipher MOA from inches.
The most accurate turret adj. that I have is 0% on a Tasco 6-24x44 cheap-o. Most of my scopes are from 3% -10% with a couple that are actually 20% off! Scope price to error percentage ratio? I've found little to justify a $1200 scope over a $200 scope IF turret accuracy is the only criteria.......... & please don't jump all over that statement until you read it a second time.

To clarify : If I find that my turret 'clicks' are actually 0.144" @ 50 yds then here is my calculation (at home, not in the field) :
0.144 x 2 = 0.288" @ 100 yds.
0.288" / 1.0472 ("/MOA) = 0.275 MOA (You'll notice I didn't add "@ 100 yds.")
0.25MOA (what it should be) / 0.275 (what it is) = 0.91

In other words, I make a note on my cheat-sheet that all of the following MOA turret adjustments take into account that the turret is "fast" by 10% so if my software tells me to crank the scope 24.5 MOA (for a 920 yd shot w/my .243Win.), my cheat-sheet will actually list 22.3 MOA. (24.5 x 0.91 = 22.3 MOA) Remember, that error of 2.2 MOA @ 920 yds is about 21".... and that's a huge miss if you're prairie dog shooting 'cause they're only 8"-12" high

It takes some work in the office and on the bench but a speadsheet program allows that calc to be preset so all of the adjustments print out correctly.

I hope that this helps a few shooters who wonder why their ballistic program is so far off.

 

[the rifleer]

to put it simply, on your scope (usually) one click is 1/4'' at 100 yards. At 200 yards one click is 1/2''. At 300 yards 1 click is 3/4''.... At 1000 yards one click is 10'', so if you have 52 clicks, at 1000 yards thats 520 inches.

 

[blackops]

Depends on what your clicks are...I'm guessing 1/4. Your MOA (inch) will change in incriments of 100yds. 1 click at 100 will move your POI 1/4 inch and so on.

1/4--100
1/2--200
3/4--300
1----400 etc etc

 

[ms6852]

It's a quadratic equation. From your zero whether its 100 or 200 yds or whatever you start from there. Blackops explains it in the most simplistic form there is.

 

[tatasta]

Thank You!

Hey,

Thank you everyone. All of that informtion was very helpful.

I really appreciate everyone's positive replies.

Thanks again

 

[Zak Smith]

Don't think in terms of inches. Think in terms of moa (or mils or iphy depending on your scope setup) of correction



article | Practical Long-Range Rifle Shooting, Part II - Optics

 

[mickeydim468]

tataska,

Here is a simple trajectory chart i made up for my 300 Win Mag with a muzzle velocity of 3233fps using a 165 Gr Hornady Interlock SPBT bullet. The point is, I have not hidden the formulas, and you can look at how the mathematics works at each distance. I have only taken it out to 1000yds, but it should give you a good basis for learning the clicks to drop at x-distance calculations.

This is an excel worksheet that I had to zip in order to upload it for you. Just un-zip it and open it with excel. Feel free to scan it for a virus first, If this does not work for you, PM me your e-mail address and I will send it to you in the clear!

I hope this helps!

Mikey!

 

[Bobarino]

if you have an Iphone, check out the iSnipe app. if you have an Android Phone, check out the "shooter lite" app. no more guessing or equations. i use the 'driod's "shooter lite" and it's pretty accurate but not 100%. there's Balcalc for windows mobile phones, but windows phones suck. if you have internet access, there are pleny of online ballistics calc wesites you can get to too.

I'm not a fan of BDC reticles because they only work right with one load in one gun under one set of atmospheric conditions. a Mil/Mil scope is the way to go in my opinion. very easy math and you can measure and compensate on your target very quickly.

 

[blackops]

Don't think in terms of inches. Think in terms of moa

For someone just learning? Why?

 

[benzy2]

Why not? MOA is MOA, regardless of range. Learn the units, then learn how to use them. Ballistic tables aren't labeled in 1/4" at 100 yard adjustments. They are labeled in MOA/MIL. Why not learn the system to start? Understanding MOA is the first step in shooting at multiple distances. Stating that 1 click moves the impact 1/4" at 100, 1/2" at 200 is fine, but it doesn't explain why. MOA explains why.

 

[Uncle Mike]

MOA, MIL, IPHY, they all are units of measurement.

What's easier to adjust for the average shooter on his/her 1/4" per 100y Turret Value scope, simple 'inches', or doing the conversion thing to arrive at MOA or MIL?

Let's see, his bullet drop was 91" at 700y...that would be 13 IPHY, 12.4 MOA or 3.6 MILS of adjustment needed to hold dead on and not hold over for a hit on target.

Now what does the guy have to do, convert the IPHY and MOA to his scopes Turret Adjustment Value, same with MILS.

How many 'clicks' on his scope is 13 IPHY, 12.4 MOA, or 3.6 MILS? Too much ciphering!

1 IPHY @ 700y is 7"..........13 IPHY X 7" = 52 clicks needed
1 MOA @ 700y is 7.329".....12.4 MOA X 7.329" = 90.8/1.750" = 51.9 clicks needed
1 MIL @ 700y is 25.2"........3.6 MILS X 25.2 = 90.72/1.750" = 51.8 clicks needed

The easy ways:

A) Bullet Movement @ Target (in inches) / Range to Target (in Inches) X 100 = Come-Up in MOA.

B) Come-Up in MOA / Scopes 'Turret Adjustment Value' = Amount of 'Clicks' Needed

OR.....
A) .250" (Scopes Turret Adjustment Value @ 100y) X 7 (for 700y) = 1.750" (amount 'each' click will move your POI @ 700y)

B) 91" (Amount bullets drops at 700y) / 1.750" = 52 (Clicks needed to hold 'dead on' @ 700y)

ie... .250 X 7 = 1.750 then 91" / 1.750" = 52

Clear as mud, huh? lol

 

[adobewalls]

For me its just easier to think in MOA than it is in "clicks."

Thinking in MOA, allowed me to establish a pattern to the adjustments. For example, recalling off the top of my head the adjustments to 600 yards for my rifle:

0 MOA = 100
2 MOA = 200
5 MOA = 300
8 MOA = 400
12 MOA = 500
16 MOA = 600

See the pattern? 2 MOA difference, 3 MOA difference, 4 MOA difference, etc.

And the pattern continues somewhat based on ballistics programs (but I have not validated these.)

21 MOA = 700
26 MOA = 800
32 MOA = 900
38 MOA = 1000

Are these the exact adjustments; no. But they have proved close enough for the .308 to get on target fairly quickly once I adjust to the local conditions.

For instance depending on the weather, the adjustment for shooting to 600 in Summer is actually 14.5 to 14.75 MOA; while in the cold of winter it can be 15.5 to 16.0 MOA. But I remember these because I remember the pattern.

 

[Zak Smith]

There is no need to deal in true linear inches at the target. Scopes are calivrated in angular units not linear units because linear units change based on the target distance. Use moa or mils from the ballistic program or your measured data and apply that directly to the scope.

 

[blackops]

Learn the units, then learn how to use them

Ha thanks dad! Actually I learned how to utilize MOA a long time ago. My reference was for a beginner or to keep it simple. Playing with decimals and mils isn't the most simplistic ranging system to start out with. Most of you who suggest that paticular method are more anal about accuracy than most and have far more experience. Then there are some who claim to be and couldn't shoot the broad side of a barn. Inches keeps it simple and with little adjustments can get you on target fairly quick. So gripe all you want about MOA or mils or whatever you want. If you break it down in inches most anyone can utilize the system.

 

[blackops]

Clear as mud, huh? lol

Good one Mike!

Scopes are calivrated in angular units not linear units because linear units change based on the target distance.

Exactly! You have spent some time behind a rifle obviously and are well educated in that respect. Looking through a PMII everyday must be a tough life for you! lol Remember that not everybody is on the same level though.

 

[Zak Smith]

Ranging is completely separate from the discussion of how to compute and apply elevation data to the scope.

Using linear inches at the target is absolutely more complicated than using the native angular units of the scope.

I do shoot great scopes but it's not relevant. I teach using angular units to students with any scope with knobs or a calibrated reticle - cheap or expensive- because it is the most effective way to do it period.

 

[Acera]

tatasta spend $50 and order Shooter Ready. Spend a few weeks going over and over the simulations and you will be good to go.


http://www.shooterready.com/

 

[Uncle Mike]

Using linear inches at the target is absolutely more complicated than using the native angular units of the scope.

How's that?

If your 2 MOA off at 700y, that is 14.625".....still 14 and 5/8" inches off.

So, dial on 2 MOA worth of correction, on the turret, to get our hypothetical shooter on target. Uh oh, out comes the sliderule and the 'conversion' from MOA to inches, the format his scope adjusts in, begins.

I understand what your saying, and totally agree, if one is intimate with MOA or MIL application and data, but the average guy thinks about everything in either inches or dollars! lol


He fires the shot, measures his hit compared to his point of aim and discovers he is the 14.625" low, now what.....?

He's needs to adjust 2 MOA but those darn numbers on the top of his turret says 1/4"/100y, nothing about MOA or MIL.

Quarters are easy, he multiplys a quarter(.250") by 7(700y) and finds it to be 1.750"...the amount each click moves his 'bullets strike' at 700 yards.

Ok, so now our hypothetical shooter has to divide his displacement, or how far off target he is(14.625") by how much each click moves his point of aim at 700y(1.750") and he finds out he has to dial on 8 clicks in the up direction. (14.625"/1.750" = 8)

If he were to use MOA or MIL, he has to decide how many MOA or MIL each click moves his point of impact at 700y. Painful at best for the non-MOA/MIL guy!

Don't get me wrong, I use MILS predominantly when shooting, but MILS are not as 'fine tuned' as MOA/Inches, and had I not been trained with this method, I would use what I could relate to the easiest, inches!

I guess a man could use the 1.832" for MOA in place of the 1.750" for inches (IPHY) but even if his scope is truly calibrated in MOA, or angular units, the error between inches (IPHY) and MOA at 700y is a whopping 82 thousands of an inch!

True angular measurement is superior in this realm, but inches will get you there, inch by inch! lol

 

[MCMXI]

He fires the shot, measures his hit compared to his point of aim and discovers he is the 14.625" low, now what.....?

And just how does he do that? How is he measuring the difference between POA and POI?

He's needs to adjust 2 MOA but those darn numbers on the top of his turret says 1/4"/100y, nothing about MOA or MIL.

I don't know about you but I don't have a single optic with IPHY adjustments. All of mine are either MOA or MILS and all have MIL reticles. Regardless, for all intents and purposes, IPHY is the same as MOA or so close as to not matter. 8 clicks up on a 1/4 MOA scope and 8 clicks up on a 1/4" per 100 yards scope is 0.658" difference at 700 yards ... big deal!!

 

[Zak Smith]

There is no reason to bring true linear inches into it at all. There is an "inch-like" angular unit called IPHY (inches per hundred yards, also called "Shooters' MOA") which I referred to in my first post (#10) in addition to moa and mils as an angular system to use.

The most convenient measurement device the long-range shooter has at his disposal is the scope itself, whose reticle has demarcations by definition in angular units (IE it has no knowledge about linear distance) which are typically moa, mils, or iphy. A hit or a miss can be located through the scope itself using the reticle demarcations and that self-same angular correction applied to the knob (if its units match) to get the POI where he wants it.

Linear inches are a non-starter. If your data card has 43 inches of drop at 450 yards and 78 inches of drop at 650 yards, how many moa (or clicks) do you need to add to get from 450 to 650? Now that involves a bunch of math that effectively converts both to angular units first anyway!

If your data simply has the angular corrections, e.g.

450 - 9 MOA
650 - 11.5 MOA

then to figure out the change: you're at 450 with 9 MOA so you need to add another 2.5 MOA to get to 650. Simple, basically no math. You just dial the knob to 11.5 from 9.

If you need to make "corrections" in moa, like "the hit was a foot high", pretending the clicks are iphy/shooter's moa will only have an approx 5% error, which will not be enough to notice. (You are correct that applying enough elevation to hit a 1000-yard target using iphy but with a moa knob will result in a miss.)

Also, way more scopes are moa than iphy.

-z

 

[tatasta]

Thank you all very much. I really appreciate the help!

I know enough to be dangerous....