Factory Ammunition Trajectory Tables
The more a shooter knows about a bullet's path, the better that shooter will be able to adjust his or her aim to compensate for gravity and the more confident the shooter will be.
Often called trajectory charts or ballistics charts, trajectory tables indicate the affect gravity has on a bullet's flight path. Simple trajectory tables are conveniently provided by ammunition manufacturers. The tables are available on ammunition manufacturers' websites, in their advertisement brochures, or sometimes printed right on the ammunition boxes. (Excerpts from certain trajectory tables can be selected and viewed below. These tables do not reflect the ammunition offered by any particular manufacturer. Also, not all ammunition types are included.)
Ammunition manufacturers provide trajectory tables for your convenience. But, did you know those trajectory tables may not be accurate for your shooting environment or for your firearm? In fact, they are accurate for very few situations. Take a look at the sidebar to the left. The conditions used to calculate the factory ammunition trajectories are listed. How often do you hunt at sea level - when the temperature is 59 degrees? Probably not very often. The conditions where you hunt or shoot probably be different - maybe drastically different.
A how high is the scope on your rifle? It may actually be 1+1/2 inches above the center of the chamber - or it may not be.
What about the muzzle velocities? Those are the muzzle velocities from the test guns. Barrel length, rifling rate of twist, and bore condition affect muzzle velocity. The advertised muzzle velocity will probably be different than the muzzle velocity of your rifle. Therefore, the basic trajectory tables provided by ammunition manufacturers probably do not show the exact trajectory of your rifle in your hunting environment. They are useful for comparing trajectories of different bullet types and weights and between the various cartridges since they are all based on the same conditions. But they do not accurately indicate the trajectory of your particular rifle.
Ammunition manufacturers would like to provide trajectory tables specifically for your rifle and your hunting environment right on the ammunition carton or in their brochures. They really would like to. But they cannot predict where you will hunt. Even if they could, atmospheric conditions change continuously. They cannot possibly provide trajectory information for all the possible conditions you - and everyone else - may encounter. So the ammunition manufacturers provide trajectory tables based only on standard atmospheric conditions. That is better than nothing.
Custom-made trajectory tables for your rifle, ammunition, and your shooting environment sure would boost your shooting confidence. Where can you get custom-made trajectory tables? You can compile your own trajectory tables.
One way to compile customized trajectory tables for your rifle and its ammunition is to go to the rifle range and shoot several boxes of ammunition at paper targets set at various distances then walk downrange repeatedly to actually measure and record the trajectory. You could do so if you live near a rifle range that extends to the maximum effective range of your rifle - and you do not mind wasting several boxes of expensive ammunition - and if you actually had the time to do it that way. Then you could hope atmospheric conditions will not be drastically different on the day you finally get to go hunting or shooting. Yes, you could do all that. But there is a much easier, faster, more reliable, and less expense way to compile your very own customized trajectory tables.
That much better way to customize trajectory tables for your gun is to use a ballistics software program. There are several computer-based ballistics programs available. They are all easy to use. After installing one onto your computer, you can select your rifle's caliber and chamber plus your ammunition's bullet weight and bullet type from a database. Next you enter current or forecasted atmospheric conditions, inclination or declination angle, desired zero range, intermediate range increments, wind speed, wind direction, actual scope height, and muzzle velocity. Then you let the program perform the ballistics calculations! A trajectory table will appear customized for your rifle and your hunting environment; one with more information than you will find on ammunition manufacturer trajectory tables. You can choose to print your trajectory table right from the program or to tweak it then print. Now, doesn't that sound much easier than the previous method? It really is easier. And it is so much faster and less expensive too. Think of all the time and ammunition you could save. Now you will have more time and ammunition to practice shooting at the range. And your shooting confidence will soar if you refer to a trajectory table customized for your rifle, ammunition, and hunting environment!An original About-Shooting article Share this article with a friend