**Crossbow Arrow & Bolts, Trajectories.** **What is trajectory.** In arrow flight, trajectory refers to the exact arcing path the arrow travels from the crossbow to the target downrange, as soon as the arrow leaves the power of the bowstring it is subjected to atmosheric drag (slowing it down) and gravity (pulling the arrow down to earth). As the arrow travels downrange it is constantly slowing down and dropping toward the ground, the further it travels, the faster it falls to the ground.
**It's all about the velocity.**
One of the first things to understanding crossbow arrow trajectories is what are the guiding principals that highten or flatten trajectories. To sum this up, it falls to one word __velocity__. When you look at the normal distance that deer are harvested with archery equipment, this would be from 10 yards to 30 yards, there is very little difference between light arrows and heavy arrows when fired at the same velocity within this yardage. The below charts will bear out this fact.
20 Inch __300 Grain__ Crossbow Arrow (Actual Drop) | Range/Velocity | 200 f.p.s. | 250 f.p.s. | 300 f.p.s. | 350 f.p.s. | 400 f.p.s. | 10 Yards | - 5 | - 3 | - 2 | - 1 | - 1 | 20 Yards | - 18 | - 12 | - 8 | - 6 | - 5 | 30 Yards | - 42 | - 26 | - 18 | - 14 | - 11 |
20 Inch __400 Grain__ Crossbow Arrow (Actual Drop) | Range/Velocity | 200 f.p.s. | 250 f.p.s. | 300 f.p.s. | 350 f.p.s. | 400 f.p.s. | 10 Yards | - 5 | - 3 | - 2 | - 1 | - 1 | 20 Yards | - 18 | - 12 | - 8 | - 6 | - 5 | 30 Yards | - 42 | - 26 | - 18 | - 14 | - 11 |
**Sight compensation of trajectory.**
The sights on a crossbow compensate for arrow drop by their installed height and not all sights are installed at the same height so not all crossbows shoot the exact same trajectory in appearance. Scope sights have an advantage as they can easily be raised higher above the flight rail by simply installing higher rings, when this is done the crossbow will sight-in differently and appear to have a flatter trajectory, which is a good thing. **Sighting-in your crossbow properly to compensate trajectory.**
When you properly sight-in your crossbow for hunting you want to have a flat trajectory, the flatter the better. To achieve this the arrow will actually intersect with the line of sight twice, giving you a dead center hold on the target for many yards without hold-over or hold-under.
**Four terms to know when properly sighting in a Crossbow.** **1.** __Point Blank Range__; Point blank range when sighting in a crossbow is the first point at which the line of sight intersects with the arrows path in the arrows trajectory arc. **2.** __Mid-Range Rise__; Mid-range rise when sighting in a crossbow is the highest point in the arrows trajectory between the point blank range and the true zero point. **3.** __True Zero__; True zero when sighting in a crossbow is the second point at which the line of sight intersects with the arrows path in the arrows trajectory arc. **4.** __Maximum Point Blank Range__; Maximum point blank range when sighting in a crossbow is the height of the mid-range rise and the arrow drop beyond true zero, both are equal in measure.
Below are some common sight-in ranges to help you find a good zeroing in point. Also these are for low mounted scopes and most peep and pin sights.
Trajectory For A __10 Yard Sight-In__ Using 300 - 400 Grain Weight Arrow. | Range/Velocity | 200 f.p.s. | 250 f.p.s. | 300 f.p.s. | 350 f.p.s. | 400 f.p.s. | 10 Yards | 0 | 0 | 0 | 0 | 0 | 20 Yards | - 8 | - 5 | - 4 | - 3 | - 2 | 30 Yards | - 26 | - 16 | - 11 | - 8 | - 6 |
Trajectory For A __15 Yard Sight-In__ Using 300 - 400 Grain Weight Arrow. | Range/Velocity | 200 f.p.s. | 250 f.p.s. | 300 f.p.s. | 350 f.p.s. | 400 f.p.s. | 10 Yards | + 2 | + 1 | + 1 | + 1 | + 0 | 20 Yards | - 4 | - 3 | - 2 | - 1 | - 1 | 30 Yards | - 20 | - 12 | - 9 | - 6 | - 5 |
Trajectory For A __20 Yard Sight-In__ Using 300 - 400 Grain Weight Arrow. | Range/Velocity | 200 f.p.s. | 250 f.p.s. | 300 f.p.s. | 350 f.p.s. | 400 f.p.s. | 10 Yards | + 4 | + 3 | + 2 | + 1 | + 1 | 20 Yards | 0 | 0 | 0 | 0 | 0 | 30 Yards | - 13 | - 8 | - 5 | - 4 | - 3 |
Trajectory For A __25 Yard Sight-In__ Using 300 - 400 Grain Weight Arrow. | Range/Velocity | 200 f.p.s. | 250 f.p.s. | 300 f.p.s. | 350 f.p.s. | 400 f.p.s. | 10 Yards | + 7 | + 4 | + 3 | + 2 | + 2 | 20 Yards | + 4 | + 3 | + 2 | + 1 | + 1 | 30 Yards | - 7 | - 4 | - 3 | - 2 | - 2 |
**Putting it all into perspective.**
If you look at the above chart you will notice that from 250 F.P.S. - 400 F.P.S. there is very little difference in trajectory when you sight in at the recommended distance that is supplied with most crossbows. This is very misleading as to what a true high performance crossbow will do when sighted in properly for deer hunting.
Bowhunting of any kind is a short range affair and is best kept under 35 Yards.
**Do you really need a multi range sight for trajectory compensation.**
The size of the heart/lung area is around 8 inches on a average size deer weighing 120 pounds. With having said that lets sight these crossbows with a maximum point blank range drop of 3 inches and a mid-range rise of 3 inches.
As you can see by the above picture you hold dead center of the target and the arrow will strike the vitals of a normal sized deer by proper sight setting, compensating the arrow trajectory correctly.
**Sighting-In to achieve maximum point blank range.**
200 Feet Per Second Maximum Point Blank Range, 22 Yards. | 5 Yards | 10 Yards | 15 Yards | 18 Yards | 20 Yards | 22 Yards | + 3 | + 3 | + 2 | 0 | - 2 | - 3 |
250 Feet Per Second Maximum Point Blank Range, 25 Yards. | 5 Yards | 10 Yards | 15 Yards | 20 Yards | 25 Yards | + 2 | + 3 | + 2 | 0 | - 3 |
300 Feet Per Second Maximum Point Blank Range, 30 Yards. | 5 Yards | 10 Yards | 15 Yards | 20 Yards | 25 Yards | 30 Yards | + 2 | + 3 | + 3 | + 2 | 0 | - 3 |
350 Feet Per Second Maximum Point Blank Range, 36 Yards. | 5 Yards | 10 Yards | 15 Yards | 20 Yards | 25 Yards | 30 Yards | 35 Yards | 36 Yards | + 1 | + 2 | + 3 | +3 | + 2 | 0 | - 2 | - 3 |
400 Feet Per Second Maximum Point Blank Range, 42 Yards. | 5 Yards | 10 Yards | 15 Yards | 20 Yards | 25 Yards | 30 Yards | 35 Yards | 40 Yards | 42 Yards | + 1 | + 2 | + 3 | + 3 | + 3 | + 2 | 0 | - 2 | - 3 |
Just remember that, because of arrow selection, sight selection, the speed of your own crossbow, you have to really shoot your crossbow at various ranges to map out its own true trajectory. This is only a guide to help you achieve the most effective use of your crossbow through the understanding of trajectory and proper sighting in procedure for hunting. |