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.

 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.

 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.