Crossbow Bolts 101 – Information for the Beginning Crossbow Hunter
With the use of crossbows as a hunting weapon gaining popularity rapidly across much of the country, we hear a lot of what to look for when purchasing a crossbow. Sure, it is important to research a crossbow or any other piece of hunting equipment before making a purchase. What many hunters and shooters are failing to do though is to research what bolt is best for their crossbow setup and for the species of animal they intend to shoot.
A lot of variables make up a good crossbow bolt. Until you know which bolt performs the best from your crossbow it is not as simple as walking into your pro shop and purchasing a six-pack of bolts and hoping for the best.
Bolt length, weight of the entire bolt, type of nock and shaft material should all be considered before making an initial purchase. Crossbow manufacturers have recommendations for which type of bolt shoots best and these recommendations should be followed. They will also provide the necessary information for the weight, length, and nock type for their crossbow. But, in the end it is up to each individual hunter to choose the best bolt for their crossbow using the guidelines set by the crossbow manufacture. If you do not shoot the correct arrow or nock, you run the risk of damaging the crossbow and/or yourself.
Crossbow bolts are similar in construction to that of arrows shot from compound bows. But, with many crossbows shooting more than 400 fps, the bolts need to be tough enough to prevent them from exploding when shot.
Bolts range in length from 16” to 22”. The most common length is 20-inches. It is possible to get away with a longer bolt than recommended, but anything shorter than what is recommended could cause the broadhead or field point to get caught on the crossbow rail when fired. However, we cannot think of one good reason why you would shoot a bolt longer than the manufacturers recommendations.
The total weight of the bolt includes the weight of the bolt, nock, insert, vanes, and broadhead or field point. Just about all bolt manufacturers will list how many grains each shaft weighs or how many grains are in each inch of the shaft. For example, your bolt might say 15 GPI. If your bolt is 20-inches, multiply 15 x 20 to figure your bolts weight. In this example it is 300 grains. Now all you must do is add the weight of the nock, insert, vanes and tip for a total weight.
A heavier bolt at least 400 grains not including the head will have better downrange energy and offer better penetration. Keep in mind that even though a bolt will leave the rail quickly, a heavier bolt will quickly lose power as it flies. A bolt on the lighter end of the manufacturer’s recommendations will fly faster and will give the shooter an extended range but might not get the desired penetration.
When purchasing a crossbow, the speed ratings are often rated using a 400-grain arrow. The heavier your arrow is, the slower it will fly. For example, if you your crossbow is rated at 350 fps, it will only travel at about 315 fps if you are shooting a 500-grain bolt. When thinking about kinetic energy, a lot goes into it. How fast your bow shoots, total mass of the bolt and distance traveled all plays into how much force is delivered upon impact. Keep in mind that the larger your broadhead is, more kinetic energy is required to get good penetration.
For small animals like deer and antelope, 23 pounds of energy is the minimum amount of kinetic energy needed. For bigger animals like elk and black bear the minimum is about 43-pounds and bigger animals like grizzly bears will require 63-pounds.
For every 10 yards your bolt travels, you can expect to lose 3 to 4-percent of energy. If you bolt is delivering 80-foot pounds of force at the initial shot, you can expect at 10-yards you will receive 78 to 77-foot pounds of kinetic energy. At 20-yards those numbers drop to 75 -74-foot pounds of kinetic energy.
There are several kinetic energy calculators on the internet that will help you figure out how much kinetic energy your bow is delivering. All you need to know is the fps a bolt is flying and the total mass weight of your bolt.
As far as vanes go, some people prefer the smaller 2-inch vanes over the larger 4 or 5-inch vanes. The reason some like to shoot the smaller vanes has a lot to do with the arrow front of center ratio (FOC). The smaller vanes will take a way some of the weight off the rear of the bolt. This will add to the FOC. Depending on your overall setup, smaller vanes can help improve accuracy. Once you have decided on length and the total weight of the arrow, practice shooting some bolts with different sizes of vanes to see which one flies better for you.
Nocks come in different styles and shooting the wrong one from your crossbow could result in the string jumping the nock and causing a dry fire. Dry firing any bow is dangerous and can be prevented by a little education and choosing the correct bolt combination to shoot. The two styles of nocks are half moon and flatback. Always use the knock type your crossbow is designed to shoot. Most, if not all crossbows will not shoot both styles of nocks.
Because crossbows are delivering bolts as such a high rate of speed, they are often difficult to see upon impact. This often leaves the hunter guessing where the bolt struck the animal. To combat this problem, it is a good idea to use a lighted nock. I have been using Nockturnal the last couple years with good results.
Companies are now offering expandable blades designed specifically for crossbows. They are like the same head you would shootout of your compound. I have shot broadheads that were designed for crossbows and those that were not. They both flew practically the same. Whether you plan on shooting a fixed blade or an expandable be sure to sight your crossbow in for the broadhead you intend to shoot. Even if you are shooting the bullseye at 30 yards with your field point, that does not mean a bigger broadhead will fly the same. But, with expendables, you stand a better chance of getting the same grouping you did with your field points.
When all the other bolt characteristics are figured out, it will not hurt to test shoot some different bolts to see which is best for you before making your final purchase. Even when everything is the same from one bolt to the next, they will not all fly the same.
If you plan on building your own bolts, it not complicated. Just be sure each bolt is constructed using the same components. You do not want different grains of inserts, nocks, etc. If you were to do this, no two bolts would fly the same. Even when everything should be equal you might find that one bolt is a little off.
Whether you made your own bolts or bought them from a big box store or even your local pro shop, they might not all fly the same. Compound archers are used to being able to tune a bow. With a crossbow you cannot do a lot to it. If you notice your bolts are going into the target straight you can try to twist the nock just a tad to see if that will fix the problem. If you are still not satisfied with the way that bolt is flying, you can just put it to the side as a practice arrow if you are worried about it.
Every component of the bolt will affect how it flies and even penetrates. It might seem overwhelming to try and figure all this out at first. But it is really a lot easier than you think. The crossbow manufacturers recommendations will give you a jump start. It is then up to you make the necessary little adjustments to get the bolt that flies best for you.