For anyone who knows anything about Superheroes, the phrase for Superman was always “faster than a speeding bullet”. It’s an adage designed to give the impression of great speed.
But it begs a really obvious question, exactly how fast is a bullet?
Bullets come in different calibers (diameter of the bullet) and this roughly is the determining factor in bullet speed. A 22lr caliber bullet will exit the barrel between 1200 and 1750 feet per second (820 to 1200 miles per hour). The larger .50 caliber round will be between 2800 to 3150 fps (1900 to 2100 mph). A typical 9mm handgun would be approximately 1200 fps (820 mph).
That’s quite a range but it seems the very large calibers for long range shooting have a bullet speed about twice that of the small caliber rounds.
There are a lot of factors though, and there is no simple answer to the question, so let’s walk through it.
What Do We Mean By Bullet Speed?
Speed in the real world has many different connotations and is standardized in many different ways.
We measure continental drift a lot differently than we measure train speed.
In the world of firearms, it can get pretty complicated as there are many different calibers, rifle manufacturers, ammunition manufacturers, barrel lengths, and weights.
Additionally, the range is varied, the bullet moves over a trajectory and the timeframe is quick.
To somewhat standardize the procedure the firearms industry will quote a bullet weight, for a given caliber and the speed measured is that as it exits the barrel, in essence, when the propellant stops acting upon the round.
The speed at which a bullet is moving the minute it leaves the barrel is known as the muzzle velocity.
It is normally measured in feet per second (fps or ft/s), meters per second (m/s), and occasionally you will see it quoted in miles per hour (mph).
Thus you might see a 125 grain 9mm round quoted as having a muzzle velocity of 1225 fps.
Bullet Speed By Caliber
As the speed of a bullet is quoted for a given caliber (and cartridge), it is useful to see what kind of rounds perform with respect to muzzle velocities.
What I did was go through each caliber and find the lowest and highest muzzle velocities for each caliber.
The table below is tabulated by increasing cartridge size, and usually a growing caliber. For each caliber and an average muzzle velocity is quoted.
|.22LR||0.223 in (5.7 mm)||1,500 ft/s (1022 mph)|
|5.56/223||0.224 in (5.7 mm)||3,160 ft/s (2155 mph)|
|.380 ACP||0.355 in (9.0 mm)||1,125 ft/s (767 mph)|
|9mm||0.355 in (9.0 mm)||1,200 ft/s (820 mph)|
|.38 SPL||0.357 in (9.1 mm)||1,100 ft/s (750 mph)|
|.357 Mag||0.357 in (9.1 mm)||1,500 ft/s (1022 mph)|
|.40 S&W||0.400 in (10.2 mm)||1,200 ft/s (820 mph)|
|10mm||0.400 in (10.17 mm)||1,300 ft/s (885 mph)|
|.45 ACP||0.452 in (11.5 mm)||1,100 ft/s (750 mph)|
|.308 Winchester||0.308 in (7.8 mm)||2,650 ft/s (1800 mph)|
|.30-06 Springfield||0.308 in (7.8 mm)||2,850 ft/s (1940 mph)|
|.338 Lapua Magnum||0.338 in (8.58 mm)||3,100 ft/s (2115 mph)|
|.50 BMG||0.510 in (13.0 mm)||3,000 ft/s (2050 mph)|
Firstly, this was just a table put together to find if there are any useful information that could be determined.
The range of speeds obtainable by commonly used rounds ranges from about 800 mph to 2100mph.
Something interesting to point out is that .22LR and .223 Remington have the same bullet caliber, but vastly different bullet speeds. This is as a result of the cartridge, which is designed for military purposes.
Predictably though, the rifle calibers designed for long range competitive shooting and game hunting, produce the highest velocities.
How Fast Do Bullets Travel After 100 Yards?
The second the bullet leaves the barrel it begins to slow down.
Without the force of the propellant no longer acting on the round, and air resistance taking effect the round starts the long process of slowing down.
I plugged some common rounds into a ballistics calculator and tabulated them below.
|Caliber||Muzzle velocity||Muzzle velocity – 100 yds|
|.22LR||1469 fps||1128 fps|
|9mm||1120 fps||960 fps|
|.30-06 Springfield||2800 fps||2597 fps|
|.308 Winchester||2820 fps||2598 fps|
|.338 Lapua Magnum||2800 fps||2681 fps|
So, depending upon usage, a round has lost 8 to 25% of its initial muzzle velocity after 100 yards.
What Factors Affect Bullet Speed
While there are lots of rather subjective factors that affect bullet speed like inclination of aim, temperature and twist rate, there are a few factors that make a huge difference.
- Bullet grain – This is basically the weight of the bullet. From and given caliber the bullet can range by quite a weight. A heavier bullet is harder to accelerate than a lighter one, so other things being equal a lighter bullet will exit with a higher muzzle velocity.
- Barrel length – The longer the propellant acts upon the bullet the longer the bullet is accelerating/ The longer the barrel the longer this effect acts upon the bullet. Thus a longer barrel will increase muzzle velocity.
- Cartridge – This is the amount and type of propellant behind the bullet. A 22LR bullet exits at around 1500 fps but the similar sized .223 Remington has a bigger cartridge behind it, so exits at over 3000 fps.
So a lighter bullet, in a longer barrel with a large cartridge of effective propellant will produce the highest muzzle velocity and thus speed of the bullet.
Bullet speed might be thought of as an interesting but ultimately trivial exercise.. Get struck by a bullet and you and whatever it hits takes a lethal wound.
The truth is it matters, especially at range as it’s a key component in wound lethality which is important when a bullet is used in the self defense role. Especially against armor.
The FBI has a standard test of caliber, and a round must have a certain penetration depth to be thought optimal for a defense role. If a round penetrates between 12 to 18 inches of ballistics gel then it is considered optimal. Less, and it’s not good enough, and more risks the bullet passing through a target and possibly injuring an innocent bystander.
Additionally, it is thought that a bullet must be traveling at least 250 fps to have a 50% chance of penetrating the skin.
A slower bullet is also more blown off course by the wind so it’s taken into account by long range snipers.
Bullet speed is an interesting and deep topic, but for most, it’s an interesting piece of info rather than anything practical. As most rounds are lethal beyond where they can be accurately aimed, is there anything actually wrong with that.