The Science of Ammo: How Energy and Velocity Affect Bullet Performance

By  //  May 11, 2023

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When it comes to choosing ammunition, the options can be overwhelming. With so many different calibers, bullet weights, and designs, it’s easy to feel lost.

However, there are two key factors that play a crucial role in determining bullet performance: energy and velocity. In this article, our gun store will explain how each of these elements affects your ammunition and what you need to know to make an informed choice.

Energy and Velocity 101

In simple terms, muzzle velocity is the speed at which a bullet exits the barrel of a firearm, measured in feet per second (fps). Muzzle velocity affects many aspects of a cartridge’s performance, including bullet trajectory and muzzle energy (we’ll touch on it later). Factors such as bullet weight, powder charge, and barrel length can all affect muzzle velocity. Lighter bullets are easier to accelerate, but they lose their energy more quickly and transfer less of it than heavier ones. Take 223 ammo, for example. A 36 gr JHP bullet with a muzzle velocity of 3,750 ft/s boasts 1,300 J of muzzle energy. At the same time, a 55 gr Nosler ballistic tip bullet shot at 3,240 ft/s has muzzle energy at 1,300 J. The powder charge is responsible for the amount of energy transferred to the bullet, and quantity here is as important as quality. Finally, longer barrels give the bullet more time to accelerate before meeting counteracting external forces. 

Even though muzzle velocity is an important factor in itself, it’s also part of a more comprehensive characteristic. Muzzle energy is a critical metric in firearm performance measurement that describes the kinetic energy that a bullet has once it’s fired from a gun. Essentially, it’s the force that a bullet carries upon exiting the barrel of a firearm. The formula for calculating muzzle energy is simple: Muzzle Energy (Joules) = 1/2 (Mass of Bullet x Velocity^2). Muzzle energy is often used as an indication of a destructive potential of a particular round. Interestingly enough, muzzle energy is affected by all the same factors as muzzle velocity. Heavier bullets and higher powder charges generally result in more muzzle energy. High muzzle velocity contributes to the round’s potential in the same manner. In short, the “the more, the better” rule works pretty well here.

How Energy and Velocity Impact Bullet Performance

We’ve already said that energy and velocity affect bullet performance, but haven’t given any specific examples. Now that we know what the two factors are, let’s dive into how they impact bullet performance. Here are some key takeaways:

Recoil: increased energy and velocity almost always mean more recoil. Recoil is the backward movement of the firearm the shooter experiences after the trigger is pulled. It’s directly tied to the amount of energy that is being released: the more energy, the more recoil you’ll feel. Though more often than not recoil is a necessary evil, you’d want it to be as weak as possible. It is known to throw shooters off the target and cause so-called flinching that negatively impacts your accuracy

Penetration: as we’ve said, the higher the energy, the more damage the bullet can do. This is especially true when it comes to penetration. A high-velocity bullet with a lot of energy will penetrate deeper into the target than a slower, less energetic bullet. However, that’s not something you’d want to maximize. Overpenetration causes the round to transferring only part of its energy to the target, decreasing its stopping power.

Choosing the Right Ammo

With all this in mind, how do you choose the right ammo? First, consider the range at which you’ll be shooting. At close range, the energy and velocity won’t be as important. The differences in various loads will be hard to perceive in natural conditions. If you’re shooting at a distance, though, you’ll want to choose a higher-energy round with a high velocity to ensure the bullet has enough acceleration to make it to the target and not stray away from it in the process.


When it comes to choosing ammunition, there are a lot of factors to consider, but hopefully, this article has helped you understand how energy and velocity impact bullet performance. By taking the time to consider these factors, you’ll be able to make an informed decision about the best ammo for your needs.

Remember, choosing the right ammo is just as important as choosing the right firearm, and it can make all the difference when it comes to accuracy, power, and effectiveness.