Muzzle energy

Source: Wikipedia, the free encyclopedia.
Pellet
exiting muzzle, with formula for energy overlaid.

Muzzle energy is the

muzzle of a firearm. Without consideration of factors such as aerodynamics and gravity for the sake of comparison, muzzle energy is used as a rough indication of the destructive potential of a given firearm or cartridge. The heavier the bullet and especially the faster it moves
, the higher its muzzle energy and the more damage it will do.

Kinetic energy

The general formula for the kinetic energy is

where v is the
velocity of the bullet and m is the mass of the bullet.

Although both mass and velocity contribute to the muzzle energy, the muzzle energy is proportional to the mass while proportional to the square of the velocity. The velocity of the bullet is a more important determinant of muzzle energy. For a constant velocity, if the mass is doubled, the energy is doubled; however, for a constant mass, if the velocity is doubled, the muzzle energy increases four times. In the

metres per second.[1]

Typical muzzle energies of common firearms and cartridges

Muzzle energy is dependent upon the factors previously listed, and velocity is highly variable depending upon the length of the barrel a projectile is fired from.

ballistic trauma depend on several other factors as well. There is wide variation in commercial ammunition. A 180 gr (12 g) bullet fired from .357 Magnum handgun can achieve a muzzle energy of 580 ft⋅lbf (790 J). A 110 gr (7.1 g) bullet fired from the same gun might only achieve 400 ft⋅lbf (540 J) of muzzle energy, depending upon the manufacturer of the cartridge. Some .45 Colt +P ammunition can produce 1,200 ft⋅lbf (1,600 J) of muzzle energy.[citation needed
]

Legal requirements on muzzle energy

Many parts of the world use muzzle energy to classify guns into categories that require different categories of licence. In general guns that have the potential to be more dangerous have tighter controls, while those of minimal energy, such as small air pistols or air rifles, require little more than user registration, or in some countries have no restrictions at all. Overview of gun laws by nation indicates the various approaches taken. Firearms regulation in the United Kingdom is a complicated example, but is demarked by muzzle energy as well as barrel length and ammunition diameter.

Some jurisdictions also stipulate minimum muzzle energies for safe hunting. For example, in

Big Five game, together with a minimum caliber of 7 mm (0.28 in).[4]

In

air guns with a muzzle energy of no more than 7.5 J (5.5 ft⋅lbf) may be acquired without a firearms license.[6]

6 mm (0.24 in) pellet have a muzzle velocity over 76 m/s (250 ft/s), which translates to more than 0.58 J (0.43 ft⋅lbf) of muzzle energy, or 2.0536 J/cm2 of "ratio energy". For comparison a standard baseball changeup thrown at 34 m/s (110 ft/s) has 1.951 J/cm2 of "ratio energy" which also exceeds the 1.8 J/cm2 of a real firearm while a fastball can reach over 3.5 J/cm2 or nearly double the level of a real firearm. The subsequent crackdowns by local law enforcement
led to many seizures, arrests and prosecutions of individual owners for "trafficking and possession of illegal weapons" over the years for weapons that were previously permitted.

See also

Resources

  • Edward F. Obert, Thermodynamics, McGraw-Hill Book Co., 1948.
  • Mc Graw-Hill encyclopedia of Science and Technology, volume ebe-eye and ice-lev, 9th Edition, Mc Graw-Hill, 2002.

References

  1. .
  2. better source needed
    ]
  3. Miljøministeriet
    . 2012-12-17. Ammunition. Retrieved 2015-03-10.
  4. ^ "NAPHA - Namibia Professional Hunting Assiation: Hunting Laws& Rifle Importation". napha-namibia.com. Retrieved 5 July 2015.
  5. ^ "Ab welcher Geschossenergie fallen Soft-Air-Waffen unter das Waffengesetz?" [From which muzzle energy does Airsoft guns fall under the gun law?]. www.bmi.bund.de (in German). Archived from the original on 2016-03-04. Retrieved 2015-09-17.
  6. ^ "Waffengesetz (WaffG)" [gun law]. gesetze-im-internet.de (in German). Retrieved 2015-09-19.