Figuring Drop based on "Come Ups"?

[Shawn Carlock]

Misfire,

Lots of good info on this post. My question in the form of an answer is why do you care what the inches of drop are? All that matters is knowing where to set the scope to impact where you want at a given distance and in a given condition. I highly recommend that you put "clicks" and "inches" in the closet and start to develope a chart that simply says "400 yd - 4.75" etc this will save much time and confusion.

 

[Misfire]

Misfire,

Lots of good info on this post. My question in the form of an answer is why do you care what the inches of drop are? All that matters is knowing where to set the scope to impact where you want at a given distance and in a given condition. I highly recommend that you put "clicks" and "inches" in the closet and start to develope a chart that simply says "400 yd - 4.75" etc this will save much time and confusion.

I absolutely agree with you.

My origional question was more for conversational reasons than practical application. Since I only have the click values for zero at distance "X", I was curious about the conversion to actual drop at those distances. I've heard people referencing how much a bullet from their rifle drops at a certain distance and was curious as to the method of conversion.

I basically do what Lever-hed outlined in his first post, " You should zero your rifle for 100 yds at that particular ammo, load, bullet, etc. Then, once your satisfied with that zero, practice shooting at 50 yd increments all the way out to what ever distance your shooting at.. this will giv you ACTUAL drop for each distance (and record it)and your dope chart will be all the more accurate."

I use the stock hash marks on the ".308" turret cap (ignoring the .308 part) and record which "value/mark" is zero at distance "X" for my specific rifle. Since my LRT is 1" elevation clicks it drastically reduces the amount of clicking I have to do. In order to shoot a deer at 400 yards I simply look at my drop table, dial to the 400 yard value and shoot.

This thread was an attempt to further my understanding of an aspect of long range shooting that until now I was in the dark on; it wasn't an attempt to over complicate anything.


Thanks for all the input!

Good stuff here!

.

 

[Shawn Carlock]

With you M3 turret scope it has true 1 MOA clicks in elevation. If you want a rough idea of inches of drop multiply the number of clicks x the hundreds of yards (400 yards is 4, 650 is 6.5). This will give you the inches of drop, quickly but roughly. If you want exact drop do the same thing and multiply by 1.047.

 

[Longshot38]

One needs to know wheter or not his scope adjust in Inches Per Hundred Yards (IPHY) or Minutes Of Angle MOA. Thier is a significant difference between the 2 at 1K

Not to start a fight here just looking for clarification. But an MOA is 1.047 inches. Thus the difference between doing the true calulations and working on 1 inch values at 1000 yards is only .47 inches. Thus what is the "significant difference"?

 

[jwp475]

Not to start a fight here just looking for clarification. But an MOA is 1.047 inches. Thus the difference between doing the true calulations and working on 1 inch values at 1000 yards is only .47 inches. Thus what is the "significant difference"?

The difference between a MOA (1.0472") VS 1" is not alot, but when adjusting a scope via the turrets the cumalitive amount is alot.

Example let's say that you need 20 MOA angle adjustment for a 1K shot. 20MOA X 1.0472 = 20.944 inches per hundred yards, so times 10 ='s 209.44" of verticle adjustment

Useing inches per hundred yards we get a verticle correction of 200" tha's a difference of 9.44 inches without any other variable factered in before you trip the trigger

If more correction is needed then the error is greater

 

[Longshot38]

The difference between a MOA (1.0472") VS 1" is not alot, but when adjusting a scope via the turrets the cumalitive amount is alot.

Example let's say that you need 20 MOA angle adjustment for a 1K shot. 20MOA X 1.0472 = 20.944 inches per hundred yards, so times 10 ='s 209.44" of verticle adjustment

Useing inches per hundred yards we get a verticle correction of 200" tha's a difference of 9.44 inches without any other variable factered in before you trip the trigger

If more correction is needed then the error is greater

Point well taken. I certainly see what you are talking about here 9.44 inches does translate to substantial difference. However when put in perspective that 9.44 inches translates to less then 1 MOA at 1000 yards. And while in competition this is a huge thing. It is not so much when looking in terms of hunting. With the vitals averaging 12-18" in size (or greater then a minute at that distance) you should still be able to put one in the boiler room with these values. However walk out much farther inches vs MOA become much more relevant.

 

[jwp475]

I feel that the difference is huge at distance and a 1 MOA error before anyother variables are added in is too much IMHO. While I agree that a hit in any where in the vitails is adequate, but this is challenging enough without compounding it.

 

[WildcatB]

Longshot38,

The errors add up though.

If you and your gun can shoot .5 MOA, and you are off nearly 1 MOA on your drop calc, and you have some error reading the wind say .25 MOA (if you're good), and your scope clicks are .25 MOA spacing, it can all add up to a miss or bad shot. .5 + .9 +.25 + .25 +??? >= 1.9 MOA circle of accuracy.

For me, it's important to minimize all possible errors so you have the highest probability of clean kill shot. The drop calc is the easiest variable to get right. This gives you more room for error with the other factors.

I think it's more important to get it right when shooting animals than shooting a match because of what's at stake.

Paul Stimac

 

[jwp475]

Longshot38,

The errors add up though.

If you and your gun can shoot .5 MOA, and you are off nearly 1 MOA on your drop calc, and you have some error reading the wind say .25 MOA (if you're good), and your scope clicks are .25 MOA spacing, it can all add up to a miss or bad shot. .5 + .9 +.25 + .25 +??? >= 1.9 MOA circle of accuracy.

For me, it's important to minimize all possible errors so you have the highest probability of clean kill shot. The drop calc is the easiest variable to get right. This gives you more room for error with the other factors.

I think it's more important to get it right when shooting animals than shooting a match because of what's at stake.

Paul Stimac

Acctualy it is worse than your example, becuase of the 9.44" error. Since it is an error you are not even aware of it before the shot. What this means is that the very best that you can do in the verticule plannes is 9.44" inches low. Now add in the .5 MOA which adds another 5" to the equation and as you can see the problems keeps compounding as well as the .5moa aiming error that lighting conditions can and do cause. Your circle that you can hit is lower than expected as much as 14" low, if this is not a huge huge error then I don't know what is

 

[Longshot38]

Acctualy it is worse than your example, becuase of the 9.44" error. Since it is an error you are not even aware of it before the shot. What this means is that the very best that you can do in the verticule plannes is 9.44" inches low. Now add in the .5 MOA which adds another 5" to the equation and as you can see the problems keeps compounding as well as the .5moa aiming error that lighting conditions can and do cause. Your circle that you can hit is lower than expected as much as 14" low, if this is not a huge huge error then I don't know what is

And all this conversation brings up back to one of the basic principals of Long Rang shooting. Verify your range tables with field data before attempting a shot and don't shoot unless you know you can make the shot. The tables created by ballistics software are nice and helpful but I use them as a starting point to make my own tables based on field data. I'm sure most of use here do the same.

 

[jwp475]

Longshot38, I have maybe been lucky, but I have found that wne I feed ExBall the proper Info (Velocity, BC, Barometric pressure, etc) and lock them inot sight-in conditions and then imput my field data then my program matches my drop and works as designed.

I have gone from sea level to 7400" of elevation and the program accurately correct my drop tables for me. I have been and I currently am very satisfied with ExBall