Is the number on the box going to be the number on the chronograph? Are the speed ratings on a crossbow accurate? For the most part, yes. But there are some tricks for making a crossbow faster.
The short answer to this question is “yes, generally”. A lot of people are leery about advertised speed because they see how different it is with vertical compound bows. The reason for the major discrepancy with a regular bow is the difference in draw length and arrows. To get IBO speeds for vertical bows, the speed is measured at maximum draw length, maximum draw weight, and very light arrows. Most archers will not shoot at the highest possible draw length and most use much heavier arrows than what are used to get IBO speeds. For example, my compound bow is IBO rated at 328 fps. But that speed was achieved using a 70 pound bow set at 31” of draw length. I shoot a 60 pounder at 29.5” with a fairly heavy arrow. My bow shoots in the low 290s.
With a crossbow, the draw length and weight are always the same. Power stroke in a crossbow is the same as draw length in a compound. Power stroke can’t be adjusted. Draw weight remains constant on most crossbows with just a few exceptions, one being the Parker Challenger which is adjustable from 125 to 150 pounds. The arrows used to get the speed are generally the same arrows you would use when hunting.
When we shoot crossbows through the chronograph, we typically find speeds within five to ten feet per second of advertised speed. Some of them shoot a little faster, some of them are a little slower. Keep in mind there can be some differences with things as simple as field tips. For instance, going from a 100 grain field tip to a 150 grain field tip will get you more accuracy but could also trim off as much as 20 fps from your speed. Conversely, going from a 150 grain field tip to a 100 grain field tip can pick up some major speed. I’ve also seen some fixed blade broadheads trim speed off downrange at further distances. You probably won’t see it on the chronograph but you can see it on the target range, especially at longer distances.
Going to a lighter arrow can also yield speed but you should always check with the manufacturer to be sure the arrow you choose complies with their warranty. Most companies want you to use their arrow. TenPoint offers a wide range of arrows and which arrow you choose can make a huge difference with how much speed you get out of the crossbow.
For example, the TenPoint Titan Extreme is their entry level model. You can expect to get 312 fps with the aluminum Magnum XX75 arrows that come with the crossbow. If you upgrade to the Ten Point Pro Elite carbon arrows you will pick up a few feet per second at 315 fps. However, if you go up to their ProLite arrow the TenPoint Titan Extreme will push 333 fps. That’s a full 21 ticks on the chronograph. A six pack of Magnum XX75 arrows is $41 and a six pack of TenPoint Pro Lite arrows is $56. So for $15 or $2.50 per arrow you’re getting a lot more performance.
If we look at higher end TenPoint crossbow like the new for 2014 TenPoint Venom, we’ll see the same results. The Venom ships with a six pack of Pro Elite arrows. With these arrows, the bow is rated at 353 feet per second. Switching to the Pro Lite arrows will get you almost 20 fps more at 372.
So it is possible to manipulate the numbers with a crossbow but most shooters are going to find the speed they get out of their crossbow will be pretty close to what the manufacturer says it will be.