How fast does a BB have to go to break the skin?

Air guns and BB guns are popular recreational shooting devices. While generally considered safe when used appropriately, there are risks involved when misused or handled carelessly. One important consideration is the velocity required for a BB to penetrate human skin and cause injury. Understanding the factors that determine whether a BB can break the skin can promote safer use of BB guns.

BB Gun Basics

BB guns, also known as air guns, are a type of non-powder gun that uses compressed air or carbon dioxide to propel spherical metallic projectiles called BBs. The term “BB” comes from “ball bearing,” referring to the original steel ball bearings shot by early air guns. Modern BBs are still ball-shaped but made specifically for air guns rather than ball bearings for industrial applications. They are typically copper plated steel between 4.3 and 4.5 mm in diameter, weighing around 0.33 grams.

There are three main types of BB guns:

  • Spring-piston guns use a spring-loaded piston that is compressed by a lever. When the trigger is pulled, the spring pushes a piston forward, compressing air in the chamber and propelling the BB.
  • Pneumatic pump guns use a hand pump to pressurize the air in the chamber that launches the BB.
  • CO2 guns use compressed carbon dioxide contained in a cylinder to provide the propulsion.

BB guns have lower muzzle velocities than traditional firearms. However, factors like the gun mechanism, projectile design, and compressed air pressure determine the velocity. Higher velocity BBs impart more kinetic energy and can cause greater injury upon impact.

Velocity Needed to Break the Skin

Whether a projectile from a BB gun will break the outer layer of skin depends on achieving an adequate velocity. The skin provides a protective barrier against penetration. To break through, the BB must strike the skin with enough force to rupture tissues and blood vessels.

According to a study published in Pediatric Emergency Care, BBs fired from Daisy Model 99 air rifles (a common pump-up BB gun) required a velocity of at least 113-123 feet per second (34-37 meters per second) to consistently penetrate human cadaver skin samples. BBs fired at lower velocities only occasionally broke the surface of the skin and were unable to penetrate deeper tissues when they did.

However, another study in the International Journal of Legal Medicine found that BBs fired from lower powered guns required velocities upwards of 200 feet per second (61 meters per second) to penetrate human abdominal skin reliably in most test subjects. Variability in skin thickness and elasticity across different parts of the body accounts for this discrepancy.

The Canadian Centre for Occupational Health and Safety reports BB guns using spring pistons can reach maximum velocities over 350 feet per second (107 meters per second) when firing lightweight steel BBs. Variable pump BB guns can achieve velocities up to 500 feet per second (152 meters per second). High powered CO2 BB guns may reach velocities over 700 feet per second (213 meters per second).

Based on this data, most BB guns when fired at close range are capable of propelling BBs fast enough to break the skin under the right conditions. While a higher velocity improves the likelihood of penetration, it depends on factors like skin thickness and shot angle. Shots to thinner skin over bony prominences or fired straight on rather than at an oblique angle are more likely to break the skin at any given velocity.

Kinetic Energy and Skin Injury

Kinetic energy determines how much damage a projectile can potentially cause upon impact. The kinetic energy of a BB is a function of its mass and velocity according to the equation:

Kinetic Energy = 1/2 x Mass x Velocity2

Even small projectiles like BBs can acquire significant kinetic energy when fired at high velocities. A 5-grain BB (0.33 grams) traveling 350 feet/second has around 3.5 joules of kinetic energy. In comparison, a 9mm handgun bullet has kinetic energy of around 500-600 joules.

While less than a firearm bullet, a BB still contains enough kinetic energy when fired at close range to break through the skin and damage underlying tissues, including:

  • Blood vessels – can cause bleeding, hemorrhage, and hematomas
  • Nerves – can cause paralysis or nerve damage
  • Muscle – can cause painful spasms and impaired function
  • Bone – can fracture or destroy bony tissue depending on impact area
  • Eyes – can rupture the eye, detach the retina, or damage the lens and cornea

Higher velocity BBs do even greater damage as the kinetic energy rises exponentially relative to the velocity. A BB traveling 700 feet/second has around 20 joules of kinetic energy, making it much more hazardous if it strikes vulnerable tissues or organs.

Factors Influencing Potential for Injury

Several factors besides velocity determine whether a BB gun can cause skin injuries and how severe those injuries may be. These include:

  • Shooting distance – BBs shed kinetic energy over distance. Shots at closer range have greater injury potential.
  • Aim and angle of impact – Shots perpendicular to the skin are more likely to penetrate than grazing shots.
  • Body region – BBs more easily break thinner skin overlying bony prominences near joints.
  • Skin condition – Dry, cracked, or damaged skin is more easily penetrated.
  • BB construction – Steel BBs do more tissue damage than lighter metals like copper or aluminum.
  • Gun condition – Worn barrels or mechanism issues can lead to unpredictable velocities.

Understanding these factors provides guidance on safer BB gun handling and injury prevention. Recommendations include:

  • Wearing protective eyewear when shooting.
  • Shooting at paper or metal targets rather than trees or other environmental objects.
  • Establishing a safe shooting distance away from the target.
  • Avoiding shooting in the direction of others.
  • Treating any BB gun as if it is loaded when holding it.

Safer Use Recommendations

Following basic safety practices is critical when using BB guns to avoid potential for serious injury:

Use Protective Gear

Wearing proper eye protection is essential, as BBs can cause blinding injuries. Heavy clothing or padding over vulnerable areas provides protection as well. Some choose to wear face masks, ear protection, and gloves during target practice.

Check Surroundings

Ensure a safe backstop such as a hillside or sand trap to catch stray shots. Review what objects or people are downrange to avoid unintended impacts from misses or ricochets.

Follow Safe Shooting Principles

  • Treat BB guns with the same respect given to firearms.
  • Always point in a safe direction.
  • Keep your finger off the trigger until ready to shoot.
  • Do not look down the barrel or point it toward any person.
  • Store the gun unloaded and locked up when not in use.

Supervise Children

Adult supervision is mandatory for any child using a BB gun. Review safety rules together and provide protective gear. Closely watch for unsafe handling of the gun.

Obey All Laws

Abide by all state and local regulations regarding BB gun possession and use. Many jurisdictions have restrictions on air guns, particularly regarding age limits, maximum velocities, discharge locations, and other safety requirements.


BB guns are designed for recreational target practice and are generally safer than firearms when used appropriately. However, they are still capable of inflicting serious injury when misused. BBs typically need a velocity exceeding 200 feet/second to reliably penetrate human skin in most areas. Factors like shooting distance, impact location, and angle determine whether skin will be broken. Following basic safety practices including wearing eye protection and not pointing guns toward anything you do not intend to shoot can help prevent BB gun injuries.

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