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The Best Bolt Grain for Crossbows

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The best grain for crossbow bolts is 400-450 (26-29 grams). Heavier grains will drop significantly, while lighter ones have less penetrating power. You can go as low as 375 grains (24.3 grams), but your accuracy will suffer. You want to use 18-inch (45.7 cm) bolts or longer to avoid wobbling.

This article explores the relationship between arrow weight, kinetic energy, and crossbow performance. Think of it as a “choosing the right tool for the job” guide, but for crossbow hunters. 

How Important Is Arrow Weight?

Arrow weight is extremely important. It’s one of the three main that maximize your crossbow’s performance, alongside draw weight and arrow length. But of the three, arrow weight has the most potential to improve your hunting. That’s because it directly influences kinetic energy and accuracy.

Arrow weight affects kinetic energy in a direct relationship. The heavier the arrow, the more kinetic energy it will have. And that makes it an effective tool for hunting. 

Heavier arrows also tend to be more accurate than lighter arrows. They are less affected by wind and other external factors that can cause an arrow to veer off course. 

If you are looking to maximize the performance of your crossbow, arrow weight is an excellent place to start. 

How Much Kinetic Energy Do You Need?

Man aiming crossbow at a target

For smaller animals, you need as little as 30 ft·lbs (40.7 J) of kinetic energy. You will need at least 50 ft·lbs (67.8 J) for larger animals like deer. If you are planning on hunting big game, like elk or bear, you will need even at least 75 ft·lbs (102 J)

An arrow’s kinetic energy is directly related to its effectiveness on game animals. So, 50 ft·Ibs (67.8 J) of kinetic energy means a more powerful impact than 30 ft·Ibs (40.7 J), which leads to better penetration and a quicker kill. 

How To Calculate Kinetic Energy

Kinetic energy is determined by its weight and speed. You can calculate it using the following formula: 

  • KE = ½ mv² 

Where: 

  • m = mass of the arrow (in grains)
  • v = velocity of the arrow (in feet per second)

For example, let’s say you are shooting an arrow that weighs 400 grains (26 g) at a velocity of 300 feet per second (91.4 m/s). Using the formula above, we can calculate that this arrow has a kinetic energy of 135 ft·lbs (183 J). 

How Arrow Weight Affects Velocity

Now that you know how vital arrow weight is, you might be tempted to choose the heaviest arrows possible. But it’s not that simple. The weight of your arrows also has a direct relationship with another important factor: velocity. 

Arrow weight affects velocity directly. The heavier the arrow, the slower it will travel. It takes more energy to accelerate a heavier object to the same velocity as a lighter object. 

For example, let’s say you are shooting an arrow that weighs 400 grains (26 g) and has a velocity of 300 feet per second (91.4 m/s). This arrow has a kinetic energy of 135 ft·lbs (183 J). Now let’s say you increase the arrow’s weight to 500 grains (32.4 g). To keep the same kinetic energy, you would need to increase the arrow’s velocity to 350 feet per second (106.7 m/s). 

As you can see, increasing the weight of your arrows will decrease their velocity. And as we learned earlier, speed is directly related to accuracy. So, if you are looking for the most accurate arrows, you will need to find a balance between weight and velocity. 

What Is the Best Arrow Weight for Your Crossbow?

Crossbow ready to shoot into blurred background

The best arrow weight for your crossbow will give you a balance between kinetic energy and accuracy. For most people, that is 400 to 450 grains (26-29 grams). 

Of course, the perfect arrow weight for you will also depend on the speed of your crossbow. The faster your crossbow shoots, the heavier your arrows can be. 

For example, if you are shooting a crossbow with a velocity of 400 feet per second (121.9 m/s), you can get away with shooting arrows that weigh as much as 560 grains (36.3 g). 

To find the perfect arrow weight for your crossbow, you will need to experiment with different weights and see what works best. Start with arrows on the heavy side and work your way down until you find the weight that gives you the best accuracy. 

Parting Shot

Arrow weight is an important factor in crossbow hunting. It affects the arrow’s kinetic energy, determining its effectiveness at killing game animals.

You’ll need to find the right balance between arrow weight and velocity to ensure accuracy. The idea is to experiment with different weights until you find the one that gives you the best results.

For more, check out 3 Most Accurate Fixed Blade Broadheads.

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