How accurate is this ballistic calculator by Hornady?

[noob_shooter]

http://www.hornady.com/ballistics-resource/ballistics-calculator

I just put in some simple numbers and got:

Range (yards) Muzzle 50 100 200 300 400 500
Velocity (fps) 2800 2597 2403 2039 1711 1427 1203
Energy (ft.-lb.) 957 824 705 508 357 249 177
Trajectory (100 yd. zero) -1.5 -0.1 0.0 -4.6 -17.6 -42.7 -85.1
Come Up in MOA -1.5 0.2 0.0 2.2 5.6 10.2 16.2


So zeroed at 100yds, the bullet would really drop 17.6 inches by the time it reached 300yds? So that means, i would have to hold that much over 100yds if i want to hit dead on @ 300?

 

[hammerklavier]

If you are zeroed at 100, then you need to hold it over the target 17 inches at 300 yards.

If you are sighting in at 100 for 300, then you will only hit high by a couple inches. Change the zero in the program to 300 yards and see how much it shows you'll hit high at 100 yards.

You aim for the bullseye, but zero the scope so that the bullet actually hits high.

 

[R.W.Dale]

Ballistic calculations are highly dependant on knowing YOUR muzzle velocity from YOUR rifle. A number that can differ greatly from the ammo manufacturers figures.

 

[taliv]

and the real BC of the bullet instead of the marketing BC

 

[Dr T]

The numbers are believable.

I suggest that you try it again by resetting the calculator so that the bullet is 2.0 inches high and 3.0 inches high at 100 yds.

For practical use in the area I hunt in Southwest Texas, I sight in everything (other than rimfires and varmint guns) to be 3.0 inches high at 100 yards. I take no shots beyond 300 yards and I don't worry much about holding over.

If you are hunting whitetails, you just need to hit a target the size of a 10 inch paper plate.

 

[ArmedBear]

There are a few ways to sight in a hunting rifle. Unless you are only going to shoot out to 150 yards, or unless you have a scope with a drop reticle that requires a 100 yard initial sight-in, you don't want to zero at 100 for hunting big game.

Some common ways to sight in a hunting rifle:

1. 200 yards -- common for .30-06 and the many rounds that have a similar trajectory, usually means hold 7-8" high at 300 and ~2 feet high at 400
2. 300 yards -- common for 7mm Rem Mag and similar, add 100 yards to above
3. +/-3" MPBR -- maximum point-blank range plus or minus 3". That means you calculate the maximum distance your round will go without going more than 3" above or 3" below the point of aim, then you zero accordingly. This is somewhere between 260 and 300 yards for common rounds, and will allow you to point and shoot without regard to range, out as far as MPBR.

For a discussion of MPBR and some sample numbers for real cartridges, see http://www.chuckhawks.com/rifle_trajectory_table.htm

These days, for long range shooting, there are other options, including range-calibrated turrets, various reticles, even scopes with built-in laser rangefinders. However, people can't hold any steadier when they aim, the ground is just as uneven, and wind still blows as hard, as in 1895. So, obviously, ethical hunting requires that you inject a dose of reality into the maximum range you plan to shoot in the field, no matter what modern gadgets you employ.

 

[Dr T]

For example,


Input Variables Firearm type Long Sight Height 1.5
Bullet Weight (grains) 125 Ballistic Coefficient .29
Muzzle Velocity (fps) 3200 Temperature 59
Barometric Pressure (hg) 29.53 Relative Humidity 78%
Zero Range (yards) 275 Wind Speed (mph) 0


Ballistics Table in Yards
30-06 125 gr., .29 B.C. www.hornady.com
Range (yards) Muzzle100 200 300 400 500 600 700 800 900 1000
Velocity (fps) 3200 2863 2550 2258 1985 1734 1508 1314 1161 1054 978
Energy (ft.-lb.) 2842 2275 1805 1415 1094 834 631 479 374 308 266
Trajectory ( -1.5 3.0 3.2 -1.9 -13.8 -34.7 -67.2 -115.2 -183.6 -277.6 -401.1
Come Up in MOA -1.5 -2.9 -1.5 0.6 3.3 6.6 10.7 15.7 21.9 29.5 38.3


The following table is provided as a "cheat sheet" that you can tape to your gun.
Ballistics Table in Yards
30-06 125 gr., .29 B.C. www.hornady.com
Range (yards) Muzzle 100 200 300 400 500 600 700 800 900 1000
Trajectory (275 yd. zero) -1.5 3.0 3.2 -1.9 -13.8 -34.7 -67.2 -115.2 -183.6 -277.6 -401.1
Come Up in MOA -1.5 -2.9 -1.5 0.6 3.3 6.6 10.7 15.7 21.9 29.5 38.3

 

[Dr T]

ArmedBear: I could not agree more. I settled on the 3" high rule of thumb as easier for me to remember. It works pretty well for BC's greater than .25. However, the 3" rule is based on the old Sierra +/- 5 inch definition of point blank range.

The rest of the rule of thumb is that if your muzzle velocity is M fps, then the point blank range is (M/10) yards. Thus, in my 125 gr. bullet example, the muzzle velocity is 3200 fps and the point blank range is 320 yards.

Another way of putting it is that each additional 100 fps gives you 10 more yards of point blank range.

 

[noob_shooter]

thanks guys.. i learned a lot..

the funny part is, when i used the same data but put 300 as zero, it's saying i'm 6" high at 100 yards.. ***? makes no sense to me..

 

[Dr T]

It is gravity at work.

It looks like you are using a 55 gr. bullet with a ballistic coefficient of about 0.22.

The bullet follows an arced trajectory because of gravity. With this low a ballistic coefficient, it will shed velocity quickly. At 200 yards, it will be about 2030 fps and at 300 it will be at 1698 fps. It will lose 16% of its velocity in between 200 and 300 yards.

If you use a zero range of 220 yards, you will be pretty flat out to 220 yds (2.9 inches high at 100) but then the trajectory of the bullet will begin to drop rapidly as the bullet slows down. It will be down 8.9 inches at 300 and 31.4 inches at 400.

 

[noob_shooter]

thanks DR.

got one more question..

so zeroed at 100yds and drops -17" at 300yds

zeroed at 300 and high 6" at 100yards.

why can't i hold 6" above 100yds (zeroed at 100yds) and still be dead on at 300 instead of holding above at 17"? confusing.. i've never shot pass 100yds that's why.. LOL! and i am gonna try this weekend.

 

[mshootnit]

when my great uncle got back from France after world war II he said take your 30-06 sight it in 4 inches high at 100 yds and leave it alone.

 

[Dr T]

By adjusting the elevation in the scope, you are changing the angle between the scope boresight and the barrel boresight. By adjusting the point of impact up 6" at 100 yards, you are effectively increasing the elevation angle of the barrel, and this angle determines the arced trajectory the bullet follows.

 

[Uncle Mike]

Noob...go to this site http://www.norma.cc/default.asp?Lang=2# and play with....their ballistic computer. hehehehe It will show you a visual ballistic path of your bullet, you will be able to understand why the numbers are changing as you move the 'zero' range distance.

Top right hand of page see 'Ballistics'... put pointer on it, see "Ballistics US"...click that...have fun!

 

[benEzra]

noob shooter, what kind of rifle are you using? Sight height has a big effect on zero range. For example, with an AR (sight height around 2.5"), zeroing dead on at 50 yards puts you very close to dead on at 200 yards with typical loads, but if you have a rifle with a sight line closer to the barrel (e.g., a mini-14), zeroing dead on at 50 will put you low at 200. 1.5 inches is average for a bolt-action with a low-mounted scope, but may not be typical of your rifle.