|
|
| Line 1: |
Line 1: |
| {{Refimprove|date=December 2009}}
| | Emilia Shryock is my name but you can call me something you like. One of the things he loves most is ice skating but he is struggling to discover time for it. In her expert life she is a payroll clerk but she's always needed her own business. Minnesota has always been his house but his wife desires them to transfer.<br><br>Also visit my weblog - healthy food delivery; [http://jd.krabbe.ca/diettogoreviews74620 our homepage], |
| '''Muzzle energy''' is the [[kinetic energy]] of a [[bullet]] as it is expelled from the [[muzzle (firearm)|muzzle]] of a firearm. It is often used as a rough indication of the destructive potential of a given firearm or load. The heavier the bullet and the faster it moves, the higher its muzzle energy and the more damage it will do.
| |
| | |
| The general formula for the kinetic energy is
| |
| :<math>E_k = \begin{matrix} \frac{1}{2} \end{matrix} mv^2 </math>
| |
| where
| |
| :''v'' is the [[velocity]] of the bullet
| |
| :''m'' is the [[mass]] of the bullet.
| |
| | |
| ==Calculating muzzle energy==
| |
| Care must be taken when using this formula that consistent units are used.
| |
| | |
| *In SI units:
| |
| **If the mass, ''m'', is in [[kilogram]]s and the speed, ''v'', is in [[metre per second|metres per second]], the calculated muzzle energy, ''E<sub>k</sub>'', will be in [[joule]]s.
| |
| **If the mass, ''m'', is in grams and the speed, ''v'', is in kilometres per second, the calculated muzzle energy, ''E<sub>k</sub>'', will be in kilojoules.
| |
| *In American engineering units:
| |
| :*Mass, ''m'', is usually given in [[grain (measure)|grains]] and the speed, ''v'', in [[foot per second|feet per second]] but kinetic energy, ''E<sub>k</sub>'', is typically given in [[foot-pound force]] (abbreviated ft-lbf). Most sporting arms publications within the United States report muzzle energies in foot-pound force. If ''m'' is specified in grains and ''v'' in feet per second, the following equation can be used, which gives the energy in foot-pound force:
| |
| | |
| :<math>E_k = \begin{matrix} \frac{1}{2} \end{matrix} mv^2 \times\left(\frac{1\mbox{ ft}\cdot\mbox{lbf}}{7000\mbox{ gr}\times 32.1739\mbox{ ft}\mbox{/s}^2}\right)</math>
| |
| | |
| :*When publishing kinetic energy tables for small arms ammunition, an [[Standard gravity|acceleration due to gravity]] of 32.163 ft/s<sup>2</sup> rather than the standard of 32.1739 ft/s<sup>2</sup> is used{{Citation needed|date=May 2012}}. The formula therefore becomes
| |
| | |
| :<math>E_k = \begin{matrix} \frac{1}{2} \end{matrix} mv^2 \times\left(\frac{1\mbox{ ft}\cdot\mbox{lbf}}{7000\mbox{ gr}\times 32.163\mbox{ ft}\mbox{/s}^2}\right)</math>
| |
| | |
| The bullet energy, remaining energy, down range energy and impact energy of a projectile may also be calculated using the above equations.
| |
| | |
| ==Typical muzzle energies of common firearms and cartridges==
| |
| {| class="wikitable"
| |
| |+Example muzzle energy levels of different types of firearms
| |
| |-
| |
| ! rowspan="2"|Firearm !! rowspan="2"| Caliber !! colspan="2"| Muzzle energy
| |
| |-
| |
| !ft-lbf
| |
| !joules
| |
| |-
| |
| | air gun spring ||.177 ||align=right| 15 ||align=right| 20
| |
| |-
| |
| | air gun mag spring ||.22 ||align=right| 22 ||align=right| 30
| |
| |-
| |
| | air gun PCP ||.22 ||align=right| 30+ ||align=right| 40+
| |
| |-
| |
| | pistol ||.22LR ||align=right| 117 ||align=right| 159
| |
| |-
| |
| | pistol ||9 mm ||align=right| 383 ||align=right| 519
| |
| |-
| |
| | pistol ||.45 ACP ||align=right| 416 ||align=right| 564
| |
| |-
| |
| | rifle ||5.56 × 45 mm ||align=right| 1,325 ||align=right| 1,796
| |
| |-
| |
| | rifle ||7.62 × 39 mm ||align=right| 1,527 ||align=right| 2,070
| |
| |-
| |
| | rifle ||7.62 × 51 mm ||align=right| 2,802 ||align=right| 3,799
| |
| |-
| |
| | heavy ||.50 BMG ||align=right| 11,091 ||align=right| 15,037
| |
| |-
| |
| | heavy ||14.5 × 114 mm ||align=right| 23,744 ||align=right| 32,000
| |
| |}
| |
| | |
| {| class="wikitable"
| |
| |+Average muzzle energies for common pistol cartridges
| |
| |-
| |
| !rowspan=2|Cartridge
| |
| !colspan=2|Muzzle energy
| |
| |-
| |
| !ft-lbf
| |
| !joules
| |
| |-
| |
| |[[.380 ACP]]
| |
| |{{Convert|199|ftlbf|J|disp=table}}
| |
| |-
| |
| |[[.38 Special]]
| |
| |{{Convert|310|ftlbf|J|disp=table}}
| |
| |-
| |
| |[[9 mm Luger Parabellum|9 mm Luger]]
| |
| |{{Convert|350|ftlbf|J|disp=table}}
| |
| |-
| |
| |[[.45 Colt]]
| |
| |{{Convert|370|ftlbf|J|disp=table}}
| |
| |-
| |
| |[[.45 GAP]]
| |
| |{{Convert|400|ftlbf|J|disp=table}}
| |
| |-
| |
| |[[.45 ACP]]
| |
| |{{Convert|400|ftlbf|J|disp=table}}
| |
| |-
| |
| |[[.40 S&W]]
| |
| |{{Convert|425|ftlbf|J|disp=table}}
| |
| |-
| |
| |[[.357 Sig]]
| |
| |{{Convert|475|ftlbf|J|disp=table}}
| |
| |-
| |
| |[[.357 Mag]]
| |
| |{{Convert|550|ftlbf|J|disp=table}}
| |
| |-
| |
| |[[10mm Auto]]
| |
| |{{Convert|650|ftlbf|J|disp=table}}
| |
| |-
| |
| |[[.44 Mag]]
| |
| |{{Convert|1000|ftlbf|J|disp=table}}
| |
| |-
| |
| |[[.50 AE]]
| |
| |{{Convert|1500|ftlbf|J|disp=table}}
| |
| |-
| |
| |[[.454 Casull]]
| |
| |{{Convert|1900|ftlbf|J|disp=table}}
| |
| |-
| |
| |[[.460 SW]]
| |
| |{{Convert|2400|ftlbf|J|disp=table}}
| |
| |-
| |
| |[[.500 SW]]
| |
| |{{Convert|2600|ftlbf|J|disp=table}}
| |
| |}
| |
| | |
| It must be stressed that muzzle energy is dependent upon the factors previously listed and that even velocity is highly variable depending upon the length of the barrel a projectile is fired from.<ref>http://www.ballisticsbytheinch.com/</ref> Also note that the muzzle energy does not necessarily reflect how much energy is transmitted to the target. While the above list mentions some averages, there is wide variation in commercial ammunition. A 180 grain bullet fired from .357 magnum handgun can achieve a muzzle energy of 580 foot-pounds. A 110 grain bullet fired from the same gun might only achieve 400 foot-pounds of muzzle energy, depending upon the manufacture of the cartridge. Some .45 Colt ammunition can produce 1,200 foot-pounds of muzzle energy, far in excess of the average listed above.
| |
| | |
| ==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==
| |
| {{Reflist}}
| |
| | |
| ==See also==
| |
| *[[muzzle velocity]]
| |
| *[[firearm]]
| |
| *[[foot-pound force]]
| |
| *[[free recoil]]
| |
| | |
| {{DEFAULTSORT:Muzzle Energy}}
| |
| [[Category:Ammunition]]
| |
Emilia Shryock is my name but you can call me something you like. One of the things he loves most is ice skating but he is struggling to discover time for it. In her expert life she is a payroll clerk but she's always needed her own business. Minnesota has always been his house but his wife desires them to transfer.
Also visit my weblog - healthy food delivery; our homepage,