Zero process question

[NTexas_V-Star]

I've got some people that come out and shoot, and they are trying to zero at 100 yards, and calculate the hold over for 300 yards. This is with a .308, shooting 178 grain rounds pushing 2300 FPS.

My question is, does anyone know of a mathematical process to calculate this, or would it just be better to actually zero at 300 yards ( we have a place to do this) and then shoot at 100 yards and see where it hits?

[fbodyjohnny]

dont zero for 300, im studying for sniper school, what is really helping me out with it is a nice cheap APP for Iphone, U.S. Army Sniper Manual. it has everything in there. you zero at 100 meters, confirm zero, then take note of the weather conditions, including altitude, wind both near and far, humidity etc.. but,, 300 meters is nothing to really worry about. what scope/sights are you using? what are the adjustments? 1/2 moa ? 1/4 moa ?

[Nash B.]

It would be better to just zero at 300 yards too. You'd need to know the coefficient of drag of the bullet as well as its weight and initial velocity and all that fun stuff.

[NTexas_V-Star]

dont zero for 300, im studying for sniper school, what is really helping me out with it is a nice cheap APP for Iphone, U.S. Army Sniper Manual. it has everything in there. you zero at 100 meters, confirm zero, then take note of the weather conditions, including altitude, wind both near and far, humidity etc.. but,, 300 meters is nothing to really worry about. what scope/sights are you using? what are the adjustments? 1/2 moa ? 1/4 moa ?

It's not me doing it. I'm not even sure what the gun is other than caliber, I was just told to ask that specific question.

[fbodyjohnny]

ah, yea just zero for 100 meters, if it is scoped, after you achieve your zero, remove the dials and set them back on to where the indicator on the base and the "0" on the dial line up and set the dial back on. same for windage dial. then shoot a 300 meter target, adjust for that, write down your settings. same thing for 400 meters, 5, 6, 7, all the way up to 1000. its important you keep tabs on wind, temperature, altitude, humidity. thats basicly it. if i had my book of notes here with me, i could give you the exact numbers and some simple math, but since i recently started studying, i dont quite have it burned into my memory yet.

[fbodyjohnny]

dont just zero at 300 meters, doing that will make the math more difficult to figure out a further shot. most scopes with a 1/4" moa windage adjustment and 1/2" moa elevation adjustment are PERFECT for .308 that is why the army uses a certain bullet, with a certain rifle, with a certain scope. the math is so much easier, and is easily adjustable for further shots if you're zeroed at 100 meters. hince the name " m24 sniper weapon SYSTEM "

[fbodyjohnny]

1 moa @ 100 meters is 1.125" took me long enough to remember that one lol. im definitely going to start studying harder.

[Dacotua]

I've got some people that come out and shoot, and they are trying to zero at 100 yards, and calculate the hold over for 300 yards. This is with a .308, shooting 178 grain rounds pushing 2300 FPS.

My question is, does anyone know of a mathematical process to calculate this, or would it just be better to actually zero at 300 yards ( we have a place to do this) and then shoot at 100 yards and see where it hits?

Never go by the velocity on the box or by a chart. Fire your gun over a chrony to determine your fps.

You need the bullet coefficient and weight.

You need the height of the bore to the center of the scope.

Make sure your gun is zeroed for 100 yards.

If you have a iphone download bullet drop (free) and it will give you your bullet drop. Adjust your scope for the distance and you should be close.

[fbodyjohnny]

grain+noted average velocity+distance to be fired+temperature+humidity+altitude in relevation to sea level+wind= perfect shot every time with any rifle zeroed for 100 yards/meters. bullet drop charts can only tell you what the POA will be in a PERFECT set of conditions. throw in some of the "shit" i noted above, and that bullet drop chart becomes completely useless. but we are talkin about a 300 yard target. holdoff wouldnt be any more than 1/4 mil.

[CJ]

Yes you can calculate the drop. 300 yards is so short a distance for a .308 its negligible.