Rifle Scopes Noob sight-in question

[overthere]

I mounted my Vortex scope on my 223 bolt action Savage and sighted it in at 50 yards for the purpose of taking it to 300 yards.

Sitting at the 50 yard bench I looked up the bullet drop for 223 at 300 yards. I saw some posts saying that if zeroed at 100, the drop at 300 is about 12 inches. If zeroed at 25 then the drop at 300 should be around 4 inches. I did not find information on zeroing at 50 but I figured there would be somewhere between 4 and 12 inches drop so I set the scope to shoot 4 inches high at 50, thinking this would be somewhere in the neighborhood when I got to 300.

Well, it was not. At 300 it was shooting 12 inches high. This probably makes perfect sense but I was wondering if someone could explain it to me.

1. Is it that 4 inches at 50 yards = 24 inches at 300 yards (4 * 6 to get from 50 to 300) and then the over distance bullet drop took it from 24 to 12?

2. In general, how big of a difference does the angle of the barrel to the target make when zeroing at a certain distance? For example if I zero at 50 yards from a bench such that the barrel is almost level with the target, will that produce the same results at 300 as if I zero at 50 yards from prone where the barrel is below the target, in an upward angle?

 

[Bear24]

You would probably be better served zeroing at 100 and then take your ammo and atmospherics info (bullet weight, BC, and velocity, and DA) and plugging it into a ballistic calculator. JBM is free and great but not very mobile.

What model Vortex are you using?

 

[FLIGHT762]

What you need to do is to learn to use a ballistic program and use either MOA (minutes of angle) or Mils (Millradian) and stop thinking in inches. Depending on the turret adjustments on your scope, they're either in MOA or Mils. Your calculation to shoot 4 inches high @ 50 yards resulted in you overshooting at 300 yards as you found out. You would have been closer to your 300 yard zero if you had the rifle shoot about 1.5" high at 50 yards. This would be very dependent on Sight above the bore, velocity, ballistic coefficient etc.

It's actually all math and is not difficult once you figure out your bullet drops. There are tons of learning long range shooting on the net along with a free ballistics programs. One called JBM ballistics is a good one to use. JBM - Calculations Go to this page, read it and then go down to "Trajectory" click on it and it will give you the trajectory calculator.

Try to find a long range shooter or shooters in your area who can mentor you, since you're starting from scratch. Maybe someone can make you a data drop card for your rifle and ammo to help you get started.

These videos can help:

http://www.youtube.com/watch?v=VA2PZBD5Tjg


http://www.youtube.com/watch?v=S5AGsHSIsVo




Others can chime in here as to where there are good resources.

 

[overthere]

Thanks for the replies, I will check out the JBM program.

Bear, it is a Vortex Viper 6.5-20x50

 

[victorz]

I mounted my Vortex scope on my 223 bolt action Savage and sighted it in at 50 yards for the purpose of taking it to 300 yards.

Sitting at the 50 yard bench I looked up the bullet drop for 223 at 300 yards. I saw some posts saying that if zeroed at 100, the drop at 300 is about 12 inches. If zeroed at 25 then the drop at 300 should be around 4 inches. I did not find information on zeroing at 50 but I figured there would be somewhere between 4 and 12 inches drop so I set the scope to shoot 4 inches high at 50, thinking this would be somewhere in the neighborhood when I got to 300.

It doesn't matter what distance you zeroed, the bullet drop rate is always the same. Are you sure the 4 inches you are talking about is not 4moa? 223 with 100 zero, will need 4moa to 300. If you are sure about the 4 inches drop, it might be using canted rings.

Well, it was not. At 300 it was shooting 12 inches high. This probably makes perfect sense but I was wondering if someone could explain it to me.

If you are sure about the 4 inches drop, it might be using canted rings.

1. Is it that 4 inches at 50 yards = 24 inches at 300 yards (4 * 6 to get from 50 to 300) and then the over distance bullet drop took it from 24 to 12?

Sure, usually zero at 100 is better.

2. In general, how big of a difference does the angle of the barrel to the target make when zeroing at a certain distance? For example if I zero at 50 yards from a bench such that the barrel is almost level with the target, will that produce the same results at 300 as if I zero at 50 yards from prone where the barrel is below the target, in an upward angle?

Angle make difference, but from sitting to prone is minimal. Especially within 300.

check this you will understand the angle better:
Angle Shooting

 

[nightwolf0215]

Thank you for the info Victorz. Is thhis victorr from calguns?

 

[victorz]

no, victorz from calguns