Ammunition

How to Create Your Own Ballistics Chart

ballistics chart

If you are someone who routinely shoots past 200 yards with a rifle, it would be quite helpful to know how to build your own ballistics chart/D.O.P.E. chart. By doing so, you can adjust your scope to have the cross hair line up with the point of impact at any given distance.

In a pinch, if you have a Mil-Dot reticle, you can use the Mil-Dot lines to adjust the aim. The first choice is more accurate if done correctly. The second option is a lot quicker, but a much less precise method.

What You Need

To create the ballistics chart, you need some tools and some information.

(Yes, there is math. No, it isn’t difficult math.)

ballistics chart tools and information

Where to Start

The first place to start is with the information provided by the factory. This does not matter if you are shooting reloads or factory-built ammo.

There will be some slight differences depending on which course you take there, but the factory information is always the starting point. Some factories even provide very solid ballistics calculators and they should be leaned on heavily.

An example:

I shoot a lot of .270 Winchester as hunting ammo. As such, I have a ballistic chart for that round when shot from my rifle, with hand loads.

In order to build this chart, I need to know the ballistic coefficient of the bullet, the velocity my rifle shoots the bullets at, the weight of the projectile and how consistent the velocity is. Here’s what the factory info tells me:

  • Bullet: Hornady SST #27352
  • Weight of the projectile: 140 grains
  • Ballistic coefficient: G1 BC .495
  • Powder: H414

At just over 49 grains of powder, I have a strong accuracy node despite being far from maximum pressure or velocity. When I make precision loads my ES (Extreme Spread) is about 10 fps, confirmed with my Magneto chronograph.

From my rifle, this translates to 2780-2790 fps. If you are using factory ammo, (and do not have a chronograph) they give their best guess on the side of the box.

You will need to determine the length of barrel used in their test and calculate approximate gain or loss from your barrel length.

chronograph
A chronograph is optional, but will definitely help with your ballistics chart.

Next Steps

When that rough number is obtained, a basic chart can be made to test versus known distance targets.

Pick your ballistics calculator of choice. I like both options from Hornady found here. Note the 4DOF is more designed for longer distance and to provide more advanced calculations with input from a Kestrel. Well beyond the scope of this article.

I also like the Berger Bullet calculator found here. 

Key information to input:

  • Maximum range – 500 yards. With this rifle, I won’t normally harvest deer past 400 yards.
  • Interval – I set this at 50 yards because it makes things more precise and I am only looking at a few more data points.
  • Ballistic coefficient – Factory G1 value of .495 – for longer distances, G7 values tend to work better.
  • Velocity – As I know my ES is 10 or less, I split the difference with 2785 fps.
  • Bullet weight – Factory value of 140 grains.
  • Zero – I zero my rifle at 200 yards. This choice provides no need to adjust on a deer out to 250 yards as my rise or drop is never more than 3.1” within than range.
  • Optic height – Measure this yourself, but 1.5” is standard unless you have a scope riser or an optic larger than 50 mm.

An Example Ballistics Chart

Here’s what my chart looks like:

ballistics chart example
 

As mentioned above, I do not use the ballistics chart for anything shorter than 250 yards. Considering this, I abbreviate that portion to make a more compact chart. Past 250 yards, each 50-yard mark is notated for easy extrapolation from know listed distances.

I include inches of drop and MILRADs for several reasons. Inches are intuitive and if I need to use the mildot markings or Kentucky windage, I have the information. If I have the time, my scope is in MILRADs and 1.5 MILRADs is 15 clicks.

The velocity chart is a reminder for expansion velocity. Hornady states minimum reliable expansion on this bullet is 2000 fps. This makes a 500-yard shot questionable for expansion; and thus, hunting.

The charts I use also incorporate wind drift, but that is a whole other topic. For this article, I focused solely on drop.

Fine-Tuning It

If you do not have a chronometer, the above would be the initial stage of your chart. The next step would be to do live fire confirmation, from a solid rest.

If your rifle is zeroed at 200, then your bullets should be 1.8” high on a target at 100 yards and 7.7 inches low at 300 yards. Shoot a three or five-shot group. The group average being plus or minus a half-inch is easily written off as user bobble or inconsistency of bullet velocity.

If your impacts differ significantly more than that, go back to the ballistics calculator. Fiddle with the velocity numbers to see if you can make the observed numbers work.

If the factory velocity is listed as 2900 fps and your rifle has a shorter barrel, it might give 2750-2650 fps. With a 200 yard zero, this will be noticed as higher impacts at 100 yards and lower impacts at 300 yards.

By dropping the velocity values by 50 fps a few times, the numbers should get closer to observed data. As the data gets closer, fine-tune with smaller velocity adjustments, then reprint your chart based on what matches real-world observations.

Congrats, you now have a custom ballistics chart for your bullet/rifle combination.

Have you ever created your own ballistics chart? Let us know any tips you have in the comments below!

The Mission of Cheaper Than Dirt!'s blog, The Shooter's Log, is to provide information—not opinions—to our customers and the shooting community. We want you, our readers, to be able to make informed decisions. The information provided here does not represent the views of Cheaper Than Dirt!

Comments (3)

  1. I use the Hornady (standard) ballistic charts for both the factory ammo and handloads for the three calibers that I shoot in my rifle. For my handloads, I will check the velocity with a chronograph; for factory loads I accept the manufacturer’s info.

    I print off the charts and also plot the drop. I then go to the range and check my actual performance at 50, 100, 200, and 300 yards with five shot groups. Given personal constraints, I don’t hunt beyond 300 yards, and I am looking for accuracy in MODeer (about an 8″ circle, +/- 4″ from the aim point), so variations of a few inches are not a concern within my maximum range.

    I only encountered anomalies from the factory charts one time, when my groups fell about 6″ low. It turned out to be a bad batch of factory ammo, but that saved me from taking any from that batch on a hunting trip.

  2. I don’t see how a chronograph could be optional if you expect to get any kind of accurate numbers. As a long time reloader and 1000yd shooter, I also recommend joining a reputable forum of reloaders. The collective wisdom available is mind blowing even if you just want to understand ballistics and not “roll your own”. There are many factors to consider in rifle accuracy, and to put it simply, you just cant guess at velocity and expect an accurate table to result.
    In terms of building your data, you really should have a temperature included in your chart. Also, readers unfamiliar with long range precision shooting should be aware that ANY changes to the rifle, after your chart is built (even humidity if using a traditional hinting rifle with wood chassis) will absolutely have an effect on trajectory. Temperature of the ammo has an effect on velocity, and therefore trajectory. Different projectiles, primers, and powders will also affect velocity, for the reloaders out there. Nearly anything that changes will have an effect on velocity. Not knowing the muzzle velocity leads to way too much guessing, uncertainty, and ultimately wasted ammo and/or missed game for the hunter.

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