Interpreting bullet ballistics for factory ammo?

[tobnpr]

When purchasing factory ammo, sometimes bullet trajectory ballistics are provided on the side of the box.
Muzzle trajectory is listed as -1.5, and zero at 200 yards.

Does this mean the assumption is made that the sight height is 1.5 inches above centerline of bore, and the rifle is zeroed at 200 yards?

 

[jmr40]

I've not seen any ballistics printed on a box of ammo that listed sight height. Maybe some do.

I typically see info like this taken from a box of Hornady 150 gr 308 ammo

Muzzle 3000 fps
100 yds +1.5"
200 yds 0.0"
300 yds -6.9"
400 yds -20.0"
500 yds -40.7"

Remember these numbers are a rough guide and the actual muzzle velocity could be very different from different rifles. Even from barrels of the same length.

 

[B.L.E.]

Does this mean the assumption is made that the sight height is 1.5 inches above centerline of bore, and the rifle is zeroed at 200 yards?

Yes. Most scopes are about 1.5 inches above the bore and that's where that -1.5 inches at zero yards comes from.

Here's a pretty good online ballistics calculator and you can plug in various sight heights above the bore and see it's effects.

http://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi

 

[Mobuck]

Not really. There should be some other numbers on that chart telling you the approximate elevation at other ranges when the bullet's impact is on the crosshairs at 200 yards. For instance it might 1.5" high @100 and 5" low @300. Where the "rifle is zeroed" has nothing to do with the line of sight above the bore.