What is muzzle energy?

Discussion in 'Ammunition & Reloading' started by DarinCraft, Jan 24, 2010.

  1. DarinCraft

    DarinCraft New Member

    1,159
    0
    0
    I have always used muzzle energy on Midway's site to compare or measure the "worth" of one load to another or one caliber to another. I thought this was pretty accurate until I started researching the .460 Rowland. Several claim it has the power of the 44 mag, but when I research the 44 mag I come up with velocities in the 1500's and energy in the 1200's. When I research the 460, the velocities are similar, but the energy levels at the highest are in the 800's.

    Now either my method of comparison is not accurate or the 460 Rowland is being misrepresented.

    So can someone explain or point me in the right direction so I understand on what the data actually means for ammo?

    Thanks
    Darin
     
  2. Jpyle

    Jpyle New Member

    4,828
    0
    0
    Muzzle Energy is an estimate of the kinetic energy of a projectile given its Mass (m) and Velocity (v). In rough terms the Energy is a function of mass and velocity, simple physics...E=1/2mv^2. Differences in expression, i.e. foot-pounds, etc require some additional math for comparing one cartridge to another.

    Try this site for example and more reading

    Muzzle Energy Calculator
     

  3. canebrake

    canebrake New Member

    21,833
    3
    0
    The bullet weight in grains is a intricate part of the formula.
     
  4. DarinCraft

    DarinCraft New Member

    1,159
    0
    0
    So given that data it is possible for a (now this is a extreme comparison) .22 projectile and a .50 projectile both to have 2000 ft/lbs of energy, but just based on mass alone they would not have the same impact on a soft target. Kind of like a freight train versus a Toyota Camry hitting the same object. Their force is per square foot not total energy exchanged.

    Thanks
     
  5. Jpyle

    Jpyle New Member

    4,828
    0
    0
    Possible...maybe, likely...no. .22 and .50 are calibers which have no direct bearing on energy as measured in foot-pounds. In theory a 230 gr .22 and .50 caliber bullet leaving a muzzle at 890 fps would have the same energy. Of course the .22 would need to be much longer or denser to achieve 230 grains of mass in .22 caliber. The damage caused from tissue displacement, trauma, etc is, of course, different for each caliber but the initial energy transfer would be the same. Just as an example, a grain of sand traveling through the vacuum of space at 22,000 MPH can take out a satellite. In this case the energy is skewed towards velocity, not mass but the effect is the same. Another example would be the 30mm cannon on the A-10. A depleted Uranium round is used for tank-busting because of the difference in energy over the standard 30mm round. This time its the mass of the Uranium that ups the energy.
     
  6. DarinCraft

    DarinCraft New Member

    1,159
    0
    0
    I think I wrote that wrong. My comparison would be better worded as a 250 grain .50 cal traveling at 2500 fps would have the energy of about 2200 lbs and a 50 grain .223 traveling at 4500 fps would have roughly that same 2200 lbs.

    If I understand you correctly, even though those two rounds have the same energy they will not have the same impact due to their difference in mass. The smaller bullet would simply pass through the target because it cannot transfer their energy as quickly as the larger object.

    Not trying to be a pain, I just want to make sure I understand the basic premise before I go out and research.
     
  7. Jpyle

    Jpyle New Member

    4,828
    0
    0
    That's mostly correct. The mass and velocity differences of the 2 rounds results in the same energy...the caliber determines the surface area over which that energy is transferred. In your example you are correct in assuming that the smaller caliber, faster moving projectile will pass through more readily that the bigger, slower moving round (assuming neither are hollow points or bullet types designed to deliver maximum energy transfer when any hydrostatic pressure, i.e. flesh and blood, is encountered). Think of a baseball and a knife, can't stab anyone with a baseball because the force is distributed over the contact point which is obviously smaller in a knife. Kevlar works in a similar manner by distributing the energy over a large surface area thereby preventing penetration, but leaving one hell of a bruise due to the energy release which cannot be abated or reduced, thank you Mr. Einstein. :)
     
  8. canebrake

    canebrake New Member

    21,833
    3
    0
    .223s don't pass through a soft target, they tumble and frag. Ugly wound channel!
     
  9. canebrake

    canebrake New Member

    21,833
    3
    0
    Yes but kick that baseball up from 87 mph to 3,200 fps. I think penetration will occur thank you Mr. Einstein. :)
     
  10. Jpyle

    Jpyle New Member

    4,828
    0
    0
    Absolutely...anything moving fast enough will penetrate. The baseball analogy was meant to distinguish the relative ease with which a needle or knife can be made to penetrate flesh with little force because all the force is focused to a small area compared to that of a baseball.
     
  11. DarinCraft

    DarinCraft New Member

    1,159
    0
    0
    Thank you gentlemen I appreciate the information.
     
  12. c3shooter

    c3shooter Administrator Staff Member

    21,508
    788
    113
    Two different things here- related, but different. Energy is mass(in grains) x speed (feet per second) squared, divided by 450411. For the math challenged, here is a calculator: Muzzle Energy Calculator

    The answer is in ft lbs- not lbs per square foot. One foot lb is equal to one lb falling one foot.

    HOWEVER- then we come to terminal ballistics- how well the projectile transfers energy to the target. IN GENERAL- the bigger cross section transfer energy more efficiently. Which explains expanding bullets, such as hollowpoints. But then you have rounds that de-stabilize on impact- such as .223, the Brit 38-200, etc. And pre-fragmented rounds, such as the Glaser Safety Slug, etc.

    So a 25-06 and a .25 ACP have the same diameter bullet, but the .25-06 is heavier, and much faster, and has a lot more energy. A .308 and 30-06 may use same weight/ diameter bullet, but the 06 is faster- has more energy. A 158 grain .38 Special is 21% heavier than a 125 gr .357 mag- but the mag is moving much quicker- and has more energy.

    This discussion is a long one, well suited for a least a 6 pack by the fire. Who's got the pretzels, anyway?
     
  13. spittinfire

    spittinfire New Member Supporter

    9,663
    4
    0
    I prefer peanuts....
     
  14. cpttango30

    cpttango30 New Member

    13,934
    4
    0
    Only if they are Virginia Peanuts. they are the biggest of the peanuts grown in the USA.

    Just know that the bigger something is and the faster something is moving the more it if going to effing hurt when it hits your ***.

    OK