A Problem For The Ballistically Inclined...

[bellavite1]

Her's my problem:
I went to zero my new scope for my 308 and between the wind and the scope rings coming loose it was a disaster.
Now I won't be able to get to a 100yds range for a while.
I need to achieve a 100 yds zero by shooting at a target 25 yds away.
How low should my shots impact on the target?
I don't know if it matters but here's the specs:
5/8 rings on a 30 mm scope tube
18" barrell DPMS LRT SASS
150 gr Remington Core-Lockt ammo.
Can you help?

[Backinblackrifles]

Off the top of my head I would say shoot two inches low, Should get You in the ball park I know two high would for a 5.56 Nato with a 16in. barrel. I don't really know though I got rid of my 308 in favor of the 5.56. If You have a 30-06 in the same configuration You could go of what You know on that since the two calibers are almost ballistically identical, Only way too REALLY know though is to go shoot it @ 100 no chart is gonna be tuned to You're rifle. Anyway hope this helps.

[SA Friday]

At 25 yds, your paper impact in comparison to your scope zero will essentially be the same as the distance from the center bore axis of your barrel to the center of your scope. The bullet is travelling straight from the muzzle to the paper, so your impact in comparison to where aimed should be about 2 to 2 1/2 inches low. This is a real rough estimate as the bullet from a 308 will still be travelling at an upward arc at 100 yds and depending on the set-up won't reach it's unaltered vertices till somewhere in the range of 200 to 250 yds.

[jmg8550]

A 25 yard sight in for a .308 will get you very close at 200 yards. Aim for 2-3 inches high.

[wilsonpenfam]

the ballistics calculator says 20yds 0.8in low, 40yds 0.3in low

[OgenRwot]

That's only if you know what he's getting for velocity with his loads at his altitude with his bbl at his temp etc etc.

Basically, OP, you can only get ballpark at the very best.

[mikeh1911]

The answer is 1.4 inches low from http://www.jbmballistics.com/ with the following data.
150 grain 308 bullet traveling at 2700 FPS with a bc of .4 and a zero of 100 yards. A 2.5 sight above bore, temperature of 70 degrees, humity of 30 percent, preasure of 25.00hg, altitude of 5500 ft. At 200 yards you will be 2.8 inches low or -1.8 MOA

This is still going to be a ball park figure that should get you on paper at 200 but need to shoot 100 and 200 yards to confirm.

Hope this helps.

Mike

[SA Friday]

The answer is 1.4 inches low from http://www.jbmballistics.com/ with the following data.
150 grain 308 bullet traveling at 2700 FPS with a bc of .4 and a zero of 100 yards. A 2.5 sight above bore, temperature of 70 degrees, humity of 30 percent, preasure of 25.00hg, altitude of 5500 ft. At 200 yards you will be 2.8 inches low or -1.8 MOA

This is still going to be a ball park figure that should get you on paper at 200 but need to shoot 100 and 200 yards to confirm.

Hope this helps.

Mike

My guesstimate was a little low now that I think about it. This sounds spot on. An inch or two isn't going to throw you off paper though at 100 yds.

For everyone saying to sight in high: Epic Failure in the understandings of ballistics. Feel shame