Penetration: Velocity for steel, mass for flesh?

[Vt.birdhunter]

Trying to be as unspecific as I can here to avoid overly specific answers; Im curious more about a general rule of thumb, not the exceptions.

Discussion around here came up; when shooting at steel targets, velocity seems to be a bigger factor in damaging or penetrating steel than the mass of the projectile.

On the other hand, when hunting, we generally choose a heavier load when penetration is desirable, even though it often means lower velocity and lower foot/lbs of energy.


Any truth here, or too many other factors to make these assumptions?

 

[kraigwy]

The only real assumption you can take to the bank is you never know what a given bullet will do until it actually hits.

Lets look at hunting. We are taught, and rightfully so, that you should aim at the Heart/Lung area of a critter.

Anyone who has done any hunting at all, that an animal hit in the heart lung are may or may not run 20 plus yards before it goes down, more often then not, it will run further.

Then again, sometimes they go down instantly when shot in that area. It doesn't matter if a deer is shot with a 375 H&H, or a 243 Win. You never know until its actually shot. Even then that wont tell you what your next deer will do.

We've all heard of Capt. W.E. Fairbairn's book, "Shooting to Live" (whether we studied it or not is a different matter).

Faibairn, and commander of the Shanghai Muni. Police, during the 30s when gangs were running rampant, was involved, in one manner or other in over 600 shootings. In reading his work you'll discover that regardless of what they were shot with, they often don't stop. He relates cases where an officer dumped a whole clip into a bandit and then had to pistol whip him to get him subdued. This was after several rounds of good center of mass hits.

You can never tell. In my LE CSI duties I've seen a guy live after a good chest shot with a 44 Mag. I've seen a rather large woman die almost instantly after being shot in her Large Stomach with a 22.

One thing I did take from Fairbairn's book was that almost always, someone shot in the stomach, even if not disabled, dropped their weapons to grab their stomachs. Anyone who was ever hit in the stomach with a fist or such can understand doing that.

In short, be careful with blanket statements that bullet X will drop you in your tracks while bullet Y is totally useless.

 

[Vt.birdhunter]

Not talking about "stopping power", or dropping targets.

Inches of penetration in Gel, inches of penetration is steel. Looking for data, numbers.

I've seen a guy live after a good chest shot with a 44 Mag. I've seen a rather large woman die almost instantly after being shot in her Large Stomach with a 22.

I have nothing but respect for your experience, but I would certainly think these cases to be exceptions, not the norm.

 

[kraigwy]

but I would certainly think these cases to be exceptions, not the norm.

Yes sir, I agree, they are exceptions, I think each and ever shot could be an exception. That was the point I was trying to make.

 

[TXAZ]

I don't think the answer your looking for is as simple as you want, or that your stated assumptions are necessarily a good rule of thumb. When you are looking at the 4th and 5th order equations that accurately describe the interactions involved, NOTHING is linear or nice.

Look at 2 equal energy projectiles but on the opposite ends of the mass / velocity spectrum, each with 10,000 ft lbs of energy, where the energy in the projectile is measured as 1/2mV^2:

700 grain .50 caliber @ ~ 2500 ft / sec
80,000 lb truck (100 caliber ) moving at 2 ft / sec

The .50 is going through virtually any classical target it hits, or making a heck of a deep dent, be it steel, gel, kevlar or concrete.

The truck isn't penetrating anything, but will likely start to move the target in the direction the truck is moving at the same ~2 mph ~ 2.8 ft / sec, and unlikely to even dent a paper target at a speed a little slower than a walking pace. It may move a large concrete block, but isn't going to penetrate it.

Now take that to the extreme:
If you go to a significantly smaller bullet (an electron beam) with the same 10,000 ft lbs of energy (85,000,000,000,000,000,000,000 electron Volts, and not something you want' to be around), virtually anything in the immediate path is going to be penetrated / ablated / destroyed.

You can make a similar calculation for extremely large objects that are 'gently' set down on the earth by very large cranes, that also have 10,000 ft lbs of energy transferred. Nothing penetrates, the steel it rests on doesn't warp, (although a large enough block of gel might get slightly compressed).

To your question:

"Any truth here, or too many other factors to make these assumptions?"

It really depends on a lot of factors that aren't very simple to model and as your question you raise, there are many factors that come into play.

Does that help any?

P.S. On the other hand, I'd rather have the electron beam for any shot over 10 miles.

 

[Ryder]

Design of the projectile should be taken into account. I don't use FMJ to hunt and I don't use a HP to penetrate steel.

 

[ipscchef]

About Steel

This is not really applicable to your idea of "shooting steel"
but when my bud and I were shooting competition with 1911's, we came up with a "steel specific" round. we went with 250 gr. bullets instead of the usual 230's and loaded them to "make major" about 775fps IIRC, in the belief that the heavier bullet would drop the Steel plates and knock over the "Pepper Poppers" better, especialy when you did not get an optimum hit.The heavier bullets did seem to work better, we did have a few chances to try them in practice and, of course during matches. and like I said the heavier bullet seemed to move the mass of the steel better.
For what it is worth,
Willy