Thread: A question for the doubters

This is a good illustration of the limited predictive value of energy in wound size. Same construction similar speed different diameter and energy.


106gr ELDM 6mm at 2625fps. 1622 FTLB





147gr ELDM 6.5mm at 2693fps. 2353 FTLB.






30% more energy with the 6.5mm bullet but the permanent cavity (the important characteristic) isn't any bigger.

Calibrated ballistic gel is used for such tests precisely because it closely represents results in actual tissue.

Originally Posted by gimp

This is a good illustration of the limited predictive value of energy in wound size. Same construction similar speed different diameter and energy.


106gr ELDM 6mm at 2625fps. 1622 FTLB





147gr ELDM 6.5mm at 2693fps. 2353 FTLB.


Attachment 258212


30% more energy with the 6.5mm bullet but the permanent cavity (the important characteristic) isn't any bigger.

Calibrated ballistic gel is used for such tests precisely because it closely represents results in actual tissue.

Had a think about this one last night. The larger projectile is shedding/ Imparting energy faster due to bigger surface area. That seems pretty intuitive?

Originally Posted by whanahuia

Had a think about this one last night. The larger projectile is shedding/ Imparting energy faster due to bigger surface area. That seems pretty intuitive?

It's also light for calibre by comparison. Not apples n apples

Originally Posted by Micky Duck

It's also light for calibre by comparison. Not apples n apples

A 147gr in 6.5mm is light for calibre?

Originally Posted by gimp

A 147gr in 6.5mm is light for calibre?

I was referring to the .308 offering. To be apples n apples both projectiles need to be of same make n model and at same end of weight spectrum for calibre.

Originally Posted by whanahuia

Had a think about this one last night. The larger projectile is shedding/ Imparting energy faster due to bigger surface area. That seems pretty intuitive?

I'm not quite sure I understand what you're thinking here. Why would shedding energy sooner lead to the wound cavity being negligibly different in size?

Have to remember that ballistic gel is incontrovertibly a suitable representation of wounds in actual tissue. And these results show that with the only major difference being a .5mm larger bullet and 31gr more mass, and ~30% more energy, the wound isn't physically as different as the numbers would predict if energy was a major factor in wound size.

Originally Posted by gimp

I'm not quite sure I understand what you're thinking here. Why would shedding energy sooner lead to the wound cavity being negligibly different in size?

Have to remember that ballistic gel is incontrovertibly a suitable representation of wounds in actual tissue. And these results show that with the only major difference being a .5mm larger bullet and 31gr more mass, and ~30% more energy, the wound isn't physically as different as the numbers would predict if energy was a major factor in wound size.

No its not. its a model. Its not representative. Its a standard medium, that has no difference in tissue structure. No skin. No bone, Its 18 or more inch of constants. Its a way to hold water together without any fibres.

Compare too a deer, 20mm thickness of hair and possibly foreign material, 5-10mm of very tough barrier layer, 100mm of flesh and bone, A 150-250mm cavity of low pressure and low density material, and then the first 3 again in reverse.

The heavier projectile has stopped shorter than the lighter one was what I was talking about. as too the "wound cavity" in ballistics gel. Its a sign the projectile is working, but it may not accurately show imparted energy. Thats a dubious claim.

Originally Posted by whanahuia

No its not. its a model. Its not representative. Its a standard medium, that has no difference in tissue structure. No skin. No bone, Its 18 or more inch of constants. Its a way to hold water together without any fibres.

Compare too a deer, 20mm thickness of hair and possibly foreign material, 5-10mm of very tough barrier layer, 100mm of flesh and bone, A 150-250mm cavity of low pressure and low density material, and then the first 3 again in reverse.

The heavier projectile has stopped shorter than the lighter one was what I was talking about. as too the "wound cavity" in ballistics gel. Its a sign the projectile is working, but it may not accurately show imparted energy. Thats a dubious claim.

Maybe we should go back to using pig carcasses for comparative analysis like various military forces worldwide used to do before they moved to ballistic gel which is cheaper and easier to source. Pigs were thought to be closest to human body structure for wound analysis, bullet performance.

Originally Posted by woods223

Maybe we should go back to using pig carcasses for comparative analysis like various military forces worldwide used to do before they moved to ballistic gel which is cheaper and easier to source. Pigs were thought to be closest to human body structure for wound analysis, bullet performance.

Yeah something is up with the pictured comparisons, that lets me think its not giving us a true indicator. Im not a physicist, and maybe i'm missing something?Its quite possible, this isn't things i think about every day. To my Mind the heavier projectile at same speed should have more kinetic energy and more momentum. yet the final wound channel looks similar and the penetration of the heavier projectile was less.
So what that leads me to beleive; is that maybe the elasticity of the ballistic material is covering up some info, and that the heavier projectile is transferring its energy more efficiently.

Originally Posted by whanahuia

Yeah something is up with the pictured comparisons, that lets me think its not giving us a true indicator. Im not a physicist, and maybe i'm missing something?Its quite possible, this isn't things i think about every day. To my Mind the heavier projectile at same speed should have more kinetic energy and more momentum. yet the final wound channel looks similar and the penetration of the heavier projectile was less.
So what that leads me to beleive; is that maybe the elasticity of the ballistic material is covering up some info, and that the heavier projectile is transferring its energy more efficiently.

The end product does not show how much the entire block of gel expands during the bullets passage either.
Could this expansion be aligned with blunt force trauma? Another factor in an animals death unrelated to the wound channel?

Originally Posted by whanahuia

Yeah something is up with the pictured comparisons, that lets me think its not giving us a true indicator. Im not a physicist, and maybe i'm missing something?Its quite possible, this isn't things i think about every day. To my Mind the heavier projectile at same speed should have more kinetic energy and more momentum. yet the final wound channel looks similar and the penetration of the heavier projectile was less.
So what that leads me to beleive; is that maybe the elasticity of the ballistic material is covering up some info, and that the heavier projectile is transferring its energy more efficiently.

What other model would you use other than gelatin?

Observed actual results in animals over large sample sizes would be best no doubt but not terribly practical

Gel tests in 10% gel have been shown to match penetration in tissue very well. This indicates that the rate of energy deposition is similar and the density of gel closely matches the "average" density of bodies. Fackler et al 1984, Mabbot et al 2015, etc. It is the standard used by anyone seriously working in the field.


Predictive/speculative theoretical approaches based on secondary projectile characteristics (energy) don't seem to hold up in observed data. Since the tissue we are largely shooting into (lungs and muscle) is also elastic (like gel), it appears that a lot of energy is dissipated through the elastic deformation of the temporary cavity, and the additional contribution of that to immediate incapacitation or death is small. Certainly it happens - the temporary cavity is observable and measurable - and bullets with more energy seem to create a larger temporary cavity.



The questions are:

What size of permanent wound is required in [animal] in most circumstances [tailored to meet user requirements], to incapacitate or kill within [timeframes satisfactory to the user]?
Does [cartridge and bullet selection] have the ability to create a wound of that specification within [users likely impact velocity window]?


Those shooting .223s with heavy bullets mostly seem satisfied that the data they have suggest the answer to question 2 is yes.

There appears to be another group that speculates that the answer to question 2 is no.