The crossbow community has been obsessed with velocity ever since the resurgence of the crossbow as a viable weapon for hunting. If you open any online store that is selling them, you'd see that the speed of the arrows (measured in FPS or feet per second) that are launched by each listed model is their most prominent feature.
So to what extent the arrow velocity affects the effectiveness of this type of weapon?
In short, you need as much FPS as possible without sacrificing the other parameters of a crossbow to values that make such trade-off unworthy. The overall weight of the weapon, its balance, arrow weight, ease of cocking, and precision are also important.
And of course, most of us operate within a more or less fixed budget and don't enjoy the idea of spending $3k-$4k on one of the latest and greatest models.
..., which happens to be the most important factor in regard to hunting with archery equipment.
Two main ways in which speed affects precision:
First, faster arrows have flatter trajectory, meaning they drop less as they fly toward their target. Which results in easier aiming and thus, in improved precision.
And as we know, PRECISION IS KING!
You can check this calculator to see how fast the arrows lose height at different flight speeds.
And second, faster arrows leave less time for the animal to react to the shot sound. Because most animals tend to "jump the string".
Whitetail deer is particularly proficient at doing that.
And this is a bigger problem than you may think at the moment. Given enough time, deer would duck in preparation for a big jump. And your arrow would fly over it or hit a less desirable area, like the spine of the animal.
Practice has proved that shooting with a faster crossbow reduces or entirely eliminates the probability of this.
And last but not least,
..., because of the higher momentum at the moment of impact.
Note that the above is valid if speed is NOT increased at the expense of reduced arrow weight. Meaning that we can increase the speed by simply using a lighter shaft or broadhead, but that would actually reduce the penetration potential of the arrow because momentum is mostly affected by the weight of the projectile.
Which leaves us with the only valid option for increasing the FPS of a crossbow: buying a faster model in the first place!
But let's get a bit more precise (pun unintended):
Aside from your aiming skills, animals jumping the string is the most common reason for disappointing results on hunting trips with a crossbow. So let's focus on that.
As of 2021, crossbow speeds range between 300 FPS and 500 FPS.
Models at the high end of this spectrum tend to cost a lot so we should be pretty confident the top velocities bring equally impressive results before spending the cash.
Some of you might be in the position of owning an older model and wondering if upgrading to a 400 FPS+ model would have a great impact on your hunting experience.
And the answer is: YES, IT WOULD!
Because there is a huge difference between shooting a deer with a 300 FPS crossbow and a 400 FPS (or faster) model.
Do 100 FPS make such an impactful difference?
Yes, they do.
Here are the results of a research that compared the effect of a deer jumping the string when shot using bows with different speeds at different distances:
|Arrow Speed (FPS)||20 yards||30 yards||40 yards|
For instance, we can see that at 30 yards, a shot deer would drop about 6 inches before an arrow reaches it, if said arrow travels at 258 FPS.
Considering that the vital area (heart and lungs) of a whitetail deer is 6" to 8", we can see how easy it is to miss the target when using a slower bow or a crossbow.
The second conclusion is that this drawback of shooting slow weapons can be remedied to a good extent by simply reducing the distance we attempt shots at.
The same team that conducted the above research suggested a way to calculate the effective range for each bow/crossbow model:
Divide the crossbow velocity (in FPS) by 10.
Which means that if you want to be able to reliably hit live targets at 40 yards, you better have a crossbow that is able to launch arrows at 400 FPS or more.