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brycewise
03-01-16, 18:05
I know the obvious difference between temporary and permanent wound channels. My question is what is the primary factors for what makes a temporary wound or stretch cavity more or less effective. Is it Kinetic energy transferred from mass or Velocity. Assuming that all of the impacts are in the same location...

I know that kinetic energy is measure in the formula velocity(2) + mass.
Rifle rounds almost always have a higher velocity then pistol rounds. but when you compare two rounds that have a different base for the kinetic energy such as 7.62x39 vs 5.56x 45 one receives its energy with a bias for mass, the other receives its energy with a bias for velocity.

It would seem that the one using the higher velocity for its energy would produce a greater stretch cavity with a greater initial transfer of energy but a smaller permanent wound, where as the heavier one has a larger diameter producing a greater permanent wound but a smaller temporary cavity with a less dramatic transfer of energy.

The object that uses velocity for its energy, means its energy comes from what the object is doing (going fast) vs What the object is (big and heavy)
The target that is hit by these objects acts as an opposing force. The speed from the faster object is absorbed by the target, the energy from mass from the heavier object is retained by the object. does the kinetic energy from the heavier object still have the same effect to surrounding tissue as the energy transferred from the faster object?

At what point (velocity reduction) does the energy from velocity become less effective factor in the effect caused by the temporary stretch cavity vs. the energy from mass ?

Basically at what velocity does a rifle round become more like a pistol round and less like a rifle round?

MegademiC
03-01-16, 21:33
Edited for rambling. Energy don't come from mass or velocity.

NRG= MASS * VELOCITY ^2

you need both. Cross sectional area, mass and velocity all work together to create the temp cavity. If the tc is effective depends on speed and area. Mass makes it penetrate. The stretchiness of the tissue the bullet is going through also affects how effective the tc is..

For your last question, it's about 2000 fps iirc, according to doc gkr. But again, there is no set in stone number. A 12 ga slug produces a wounding tc at much lower velocities than a .22 cal projectile will.

Edited: I stated 1200 for some reason, it's 2000.