How Fast Does a 9mm Bullet Travel?
The 9x19mm Parabellum round is one of the most popular handgun cartridges in the world. It's a top choice for everyone from law enforcement and military to professional security personnel and civilians. But what makes this round so popular?
There are a number of reasons, but a big one is that it allows you to carry a lot of rounds in a concealable package — even in a full-size gun. It's not too big, not too powerful and not too small or weak.
The speed of the 9mm is a big contributing factor to the just-right nature of this round. Let’s take a look at why that is.
Understanding Stopping Power
Stopping power means different things to different people, but essentially it's the ability of a round to stop whatever you are shooting at dead in its tracks. Stopping power, in the simplest terms, is the energy the round delivers into the target. Stopping power is an important factor for any round, not just 9mm.
The 9mm packs a pretty solid punch due largely to its ballistics. The size and shape of the round plus the weight and speed it travels makes for an efficient round that lets you carry more ammo without sacrificing the all-important stopping power.
Why Does Speed Matter?
The energy a round delivers into the target is largely determined by two factors: the grain of the round and how fast it travels. The important thing to know is that speed is required to give a round its punch. This is actually based on laws of physics, which tell us that the force of an object is determined both by how fast the object is going and its mass. Or, to put it another way, the force of a bullet will be determined by its speed and the grain.
It boils down to Newton’s Second Law: force is equal to mass times acceleration (f=m*a), but for us, energy equals bullet grain plus muzzle velocity. Don't worry though — you don't have to be Sir Isaac Newton to understand this one.
How Is Speed Measured?
Speed is measured in muzzle velocity, which means how fast the round travels at the moment it leaves the barrel of the gun. It‘s represented by how many feet per second, or FPS, the bullet travels. Speed varies based on the round style, the weight, the manufacturer and even the firearm being used. Barrel length and twist can have an impact too.
What Affects Speed?
The speed of a round is determined by more than a few factors. The type of gun involved can impact the speed of the round, and both the length of the barrel and the twist can increase or decrease the muzzle velocity of a round. The materials that comprise the round can also speed it up or slow it down.
This is one area in particular where the manufacturer can really have an impact. To achieve a good FPS and maintain a high velocity throughout flight, many manufacturers put a great deal of research into developing ways of decreasing resistance. The air resistance as it travels is a big factor in the overall velocity of the round. The amount of powder, whether or not it's a hollow point or full metal jacket and what grain the round is all also impact speed.
What Is a Grain?
First things first: grain does not mean the amount of powder in the shell casing. That's a common misconception and one held by many a newcomer, so if it’s one you held too, don't feel bad.
A grain is actually an extremely small unit of measure referring specifically to the weight of the round itself. Just how small is a grain? Well, you would need 437.5 grains to equal one ounce. That should give you a picture of just how small this measure is. So, when your box of 9mm ammunition says something to the effect of "115gr JHP," it means it's a jacketed hollow point round that weighs 115 grains.
Does Grain Matter?
The short answer is that it depends. Obviously, if the weight of the round didn't matter, it wouldn't be plastered on every box of ammunition you buy. However, there are other factors to consider when making an ammunition purchase, like whether the ammo is for self-defense or targets. Rate of expansion and round penetration are both important, too. All of these factors make up the overall ballistic profile of a particular round, so for most people, the grain is only one factor out of many.
That being said, the weight of the round is probably the biggest factor affecting the speed of the round. The heavier the round is, the more it will be impacted by gravity — this means it will require more powder to reach the same speeds as a lighter round. Since we know that speed equals power, this can also affect other parts of the ballistic profile.
Another consideration for weight is recoil. Heavier rounds will also impact the expansion of gasses in the chamber as they are propelled from the barrel, thus changing the recoil of the gun. Similarly, an increase in powder for a heavier round also changes recoil.
Plus, keep in mind that both of those factors also change how your firearm cycles when shooting. Some guns work better with heavier rounds and some don't. Because of this, it's a good idea to see what rounds your firearm manufacturer recommends for your gun and to try to stay within those tolerances. There should be enough wiggle room to play around with types and have fun, though, so find what seems to work best with your gun and your shooting.
What Is the Standard Grain?
As with all things firearm related, it varies, and the grain of the 9mm round is no different. While 9mm rounds are made in a variety of grains from low to high, there are three weights that are common: 115 grain, 124 grain and 147 grain, with 115 grain being the most common.
How Fast Are They?
There is a general range in which the speeds do tend to fall, and for most manufacturers it's around 900 to 1500 FPS, depending on grain. As we have discussed, though, there are some factors that cause variations with regard to the speed of the round. The variations of these factors change depending on manufacturer and the type of firearm being used. However, there is a common velocity for each weight of bullet that is generally accepted as "standard." For a 115 grain round, the speed is 1250 FPS. For a 124 grain, it's 1150 FPS, and for a 147 grain, it's 950 fps.
Again, these speeds can vary by manufacturer and firearm type, and they can go considerably faster or slower depending on these variables.
How Does The Speed of a 9mm Compare to Other Rounds?
The caliber wars are a never-ending debate that spurs the kind of rancor associated with the Hatfields and McCoys, or at least Ford vs. Chevy. Many attempts have been made to settle this, but it will likely continue as long as different calibers exist.
Despite that, there are some things that you can compare between the rounds, and speed is certainly one of them. A 230 grain .45 ACP round is somewhere around 830 FPS - 950 FPS, depending on firearm. With that speed, it's similar to the 147 grain 9mm. The .40 Smith and Wesson round in the standard 165 grain is around 1130 FPS, so the 9mm of the same weight is comparable to that as well, if a bit slower on average.
Like everything else, it's going to come down to personal preference and what works best for you and your situation. The 9mm round is not the fastest round in the world, but it's hardly the slowest. It's comparable to most other common calibers used in competition and self-defense shooting, and for the majority of gun-owners in the United States, it suits their shooting needs anywhere from adequately to admirably.