Can someone PLEASE Answer this question about LONG range shooting...

N

Nalapombu

New member
Hey all,
I have asked this question on several boards and NO ONE will answer it. I know what a MOA is and other definitions, I NEED an answer to the questions below.
I have been studying a bit about long range shooting and scopes. There are a few things that I don't understand as of yet and I need for you all to answer this question for me and tell me if I am on the right track.
Here it goes...(This is all hypothetical by the way)
Lets say that I have this rifle that I have a scope mounted on. My rifle is Zeroed at 400 yards. I have a target at 1000 yards that I want to hit. Now I know that my bullet will drop 200 inches at that distance, therefore I have to move my scope 200/10 or 20 minutes of angle to be on target. Is that correct? How about this table:

500 Yards --- 10 inches drop = 2 minutes
600 Yards --- 60 inches drop = 10 minutes
700 Yards --- 100 inches drop = 14.3 minutes
800 Yards --- 150 inches drop = 18.75 minutes
900 Yards --- 175 inches drop = 19.4 minutes


Am I right about how this all works? I sure hope that I am. I was told that you take the number of inches that the bullet drops at a given distance and divide it by the distance divided by 100 (900 = 9 and so on).
If you all tell me that I am right about this it will make my day. If I am wrong then please give me the answer so I can stop being irritated about it. It really is bothering me a great deal.
I am confident that someone can help me out with the answers on this board. I am just frustrated at the other boards because I get responses that tell me everything ut the answers to the questions above.
Help a fellow brother with his pain......

Thanks for the Help.

Nala
 
Nala

If the data you have given in this scenario is correct for your rifle, then you are dead on.
You are correct...now, take a break..........;)


OOPS...........one more thing..........divide the yardage into the BULLET PATH figure, NOT the DROP figures.:)
 
200" @ 1000 yards is actually 19.1 minutes.

You are close. One MOA is APPROXIMATELY 1" per 100 yards. It is EXACTLY 1.047" per 100 yards.

This doesn't make much difference in close, but long range is a different story.

If you put in 20 minutes for your 1,000 yard dope, you will be off by .9 minutes. This means you are starting with 9.42" too much elevation.

Your chart should read:

500 Yards --- 10 inches drop = 2 minutes....................1.91 minutes
600 Yards --- 60 inches drop = 10 minutes..................9.55 minutes
700 Yards --- 100 inches drop = 14.3 minutes ..........13.65 minutes
800 Yards --- 150 inches drop = 18.75 minutes ........17.99 minutes
900 Yards --- 175 inches drop = 19.4 minutes ..........18.57 minutes

Most of the above is usually splitting hairs. Where it causes you a problem is calculating hold at very long ranges.

Assuming a 4" drop at 200 yards, if you did the same thing (used avg. vs. true minutes), your error would only be .20". Not hardly enough to worry about.

I hope that helps...I also hope I didn't screw up any of my math.
 
From Sierra's 4th reloading manual...

Bullet path height at any range can be determined by

yb(R) =[y(R)-hs]+R/Rz(hs-yz)

where
yb(R): bullet path height in inches at range R
(positive values for bullet above line of sight)
R: is range from muzzle at which yb is to be calculated in yds
y(R): is bullet drop (negative) at range R in inches
(from drop column in ballistics tables)
hs: height of sights above bore, in inches, (positive),
Rz: range at which weapon is zeroed,
yz: is drop in inches at zero range Rz, (negative), from ballistics tables.

Pause for breath.


Now, you can get your sight adjustments from the following:

A1= 95.493 ((hs-yz1)/Rz1) in MOA

where hs, yz1 and Rz1 are from the above equation;

A2= 95.493 ((hs-yz2)/Rz2) in MOA

where yz2, and Rz2 are the values from the new range / angle

SO

Sight change=A2-A1 in MOA

This allows you to obtain the number of minutes of angle and also the direction of change, ((+), bullet must be moved up on target...(-), and bullet must be moved down on target).

You'll get the value in MOA, (say for instance, +12 MOA). If your scope has 1/4 MOA per click value, this means you'll have to adjust your scope 48 clicks, and since the value is positive, it will be 48 clicks up.

What this vehkahctah mess does for you is it allows you to take into consideration the muzzle velocity of your chosen cartridge. Variations in muzzle velocity and bullet weight might throw your previous estimates off to the extent of not getting first round hits on target.


My blatant plagerism of exterior ballistics for the day. Hope you're not totally confused.
 
How about calculating it another way?

Post your caliber, bullet weight, ballistic coefficient (with velocity breakpoints if available), velocity, temperature, humidity and altitude, and I'll just run the Sierra ballistics program for you.
 
To add to the confusion.....

remember that "1/4 minute click" sights are only 1/4 minute at 100 yards.

At 200 yards, a 1/4 minute click will move impact 1/2 inch.
At 300 yards, a 1/4 minute click will move impact 3/4 inch.
At 1000 yards, a 1/4 minute click will move impact 2 1/2 inches.

This applies to iron sights or telescopic.

When you get all your calculations figured, make a chart

100 yards: 10 clicks up from bottom (or zero)
200 yards: 13 clicks up
and so forth.
Don't fiddle around with trying to figure it out every time.

By the way, find a place to shoot 1000 yards and verify your calculations prior to branding the elevation chart on the cheek piece of your rifle.
 
I do not have a rifle yet to post any ammo information for. I will change that soon though.
My reason for asking that question was to figure out how you guys done the long range scope adjusting thing. I had been reading and reading and i always saw refrences to "bringing your scope up" but I never understood how much you moved it at a given distance when you knew the bullet drop. I made up the figures that i used in the example, I done it just to practice and see if i was figuring it right. To my surprise I was on the right track, except for me disregarding the .04 extra inches per MOA. I knew that but I did not include it.
Just to give you an idea of how far off I was a week ago I will tell you this. I thought that if you had a rilfe that was sighted in at say 200 yards and your target was at 1000 and you knew that your bullet would drop say 200 inches at that distance. I thought that you would adjust your scope 100 MOA !!! I was basing my calculations on the 200 yard figure instead of the 1000 yard figure. Good thing I didn't go to the range with that priceless info.

Thanks for helping me out here fellas, I really appreciate it. Soon I will get me a rifle so I can then have some of the fun that you guys are having.

What a great place this is.....

Nala
 
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