Higher Velocity = Lower Penetration?

A

Aer454

Private
Minuteman
Oct 13, 2009
65
0
39
WA State www.TraditionalOutdoorsman.com
www.traditionaloutdoorsman.com
#1
I thought I'd ask this here on SH for a different perspective from you guys.

I was having a discussion about dangerous game cartridges and someone threw up a link talking about how beyond a certain point (1250-1300 fps) an ammo manufacturer's testing showed that above those speeds, the higher the velocity, the lower the penetration. They didn't go into any hypothesis really on the science of why that'd happen really, but after finding their results, basically saying 'the higher the speed, the faster it stops'.

Now, I know the greater the velocity (and a few other factors) allows us to reach out to greater distances. But as far as the penetration goes... I'm not 100% sold (though open minded). I mean, if you hit a nail softly... it barely sinks in the wood. Smack it hard with a hammer, and you'll drive it in. Greater force/velocity = greater results/effect, no?

But, I can understand the concept that maybe the higher speeds place greater force on the bullet, "exhagerating" it's expansion/fragmentation... which would result in less penetration. Or... perhaps, the greater velocity, increases the 'friction' on the bullet apon impact, slowing it down quicker... however I can see a few holes in that logic.

Anyway, I wanted to get a different perspective on this concept from some of you long-range guys and see what your take on it is. Thanks!

-Bill
 
#2
Re: Higher Velocity = Lower Penetration?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Aer454</div><div class="ubbcode-body">I can understand the concept that maybe the higher speeds place greater force on the bullet, "exhagerating" it's expansion/fragmentation... which would result in less penetration.</div></div>This is the way I have understood it.
 
#3
Re: Higher Velocity = Lower Penetration?

Holding all else constant higher velocity = higher kinetic energy = greater penetration. I can throw a 175 gr SMK at you and it will bounce off, if I "throw" it at 2700 fps it won't bounce...
 
#5
Re: Higher Velocity = Lower Penetration?

Oodin - With that concept in mind - would you think there may be a 'sweet spot' for maximum penetration? Like the article said, 1250-1300 for the bullets they were testing. I agree with Training Wheels, but with the theory I mentioned and you agreed with, I wonder if there would be a way to judge the optimum penetrating speeds for different rounds.
 
#6
Re: Higher Velocity = Lower Penetration?

Bullet material, weight, diameter and construction will determine at what velocity optimal penetration is acheived. A 200gr, 8mm round nose soft point bullet would probabvly pancake at 3200 fps and not penetrate much at all. But a tungsten core armor piercing bullet of the same weight and caliber would be almost unstopable.
 
#8
Re: Higher Velocity = Lower Penetration?

I don't fully disagree, but in my book sectional density and bullet construction equals penetration.

Velocity by itself does not mean more penetration, bulet weight, bullet construction, sectional density and target medium all play a role.

A frangible bullet traveling at 3200 fps will NOT penetrate as deeply as 230 grain .45 caliber hardball.

If velocity alone equaled penetration, then why does the 5.56/.223 penetrate less than the 9mm, hence the major reason for the switch from subguns to SBR's on entry teams.

No, wrap your head around this, while th e9mm will penetrate body tissue, walls and intermediate barriers better than the 5.56, the 5.56 will penetrate level III soft body armor while the 9mm won't.

The sectional density of an arrow is very high, it's velocity is not. A complete passthrough with an arrow is a very common thing.

My dad once saw a demonstration of shooting into a sand filled plastic barrel.
A 30'06 vs a compound bow. The 30'06 bullet stopped in the sand, the arrow was protruding from the far side of the barrel.

A .44 magnum revovler firing two bullets of the same weight into a large deer.
One bullet is a hollow point bullet, the other is a hard cast lead semi-wadcutter. The vast majority of times, a hollow point will stop within the body cavity, the hard cast semi-wadcutter will whistle right through.

The 30-40 Krag firing an identical 180 grain soft point bullet will penetrate deeper than the same bullet fired from a 30'06.
The bullet starts with the same sectional density, but the higher velocity of the 30'06 leads to more raid expansion, the more the expansion, the lower the sectional density.
 
#9
Re: Higher Velocity = Lower Penetration?

Stability also has a major role, which is often misrepresented as a product of velocity alone, fact it as one goes down the other typically goes up, to a certain point then they both go down. A less stable bullet (closer range, ergo higher velocity) may have a tendency to have a higher angle of attack, and yaw much, much earlier. Even if the bullet remains intact, flying sideways aint good gas mileage, through air or meat.
 
#10
Re: Higher Velocity = Lower Penetration?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Aer454</div><div class="ubbcode-body">Higher Velocity = Lower Penetration?</div></div>

That's what she said... <span style="font-style: italic">--Michael Scott</span>


Sorry, I couldn't resist.
 
#11
Re: Higher Velocity = Lower Penetration?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lakeway</div><div class="ubbcode-body">Bullet material, weight, diameter and construction will determine at what velocity optimal penetration is acheived. A 200gr, 8mm round nose soft point bullet would probabvly pancake at 3200 fps and not penetrate much at all. But a tungsten core armor piercing bullet of the same weight and caliber would be almost unstopable. </div></div>
+1

The construction of the bullet has a tremendous amount to do with the answer. If you have a solid steel bullet that will not fragment or deform: then it's simple, more velocity equals more penetration. Modern bullets have greatly varying traits when it comes to expansion and fragmentation. Varmint bullets are made to easily expand and high velocities can cause them to over expand before penetrating. Most hunting bullets for CXP2 game have medium expansion capabilities and dangerous game bullets tend to be more solid and non-expanding....to make sure the penetration is deep on thick-skinned, difficult-to-kill animals. In short, the combination of velocity and bullet selection determine expansion/penetration. Pick the right tool for the task.

In the old days when you had primitive bullets, people relied on larger calibers and higher velocities to get the job done. Modern bullets have changed this situation dramatically: allowing you to come up with very effective combos using smaller calibers and lower velocities.
 
#12
Re: Higher Velocity = Lower Penetration?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: fdkay</div><div class="ubbcode-body">I don't fully disagree, but in my book sectional density and bullet construction equals penetration.
<span style="font-weight: bold">
Velocity by itself does not mean more penetration, bulet weight, bullet construction, sectional density and target medium all play a role.

A frangible bullet traveling at 3200 fps will NOT penetrate as deeply as 230 grain .45 caliber hardball.</span>

If velocity alone equaled penetration, then why does the 5.56/.223 penetrate less than the 9mm, hence the major reason for the switch from subguns to SBR's on entry teams.

No, wrap your head around this, while th e9mm will penetrate body tissue, walls and intermediate barriers better than the 5.56, the 5.56 will penetrate level III soft body armor while the 9mm won't.

The sectional density of an arrow is very high, it's velocity is not. A complete passthrough with an arrow is a very common thing.

My dad once saw a demonstration of shooting into a sand filled plastic barrel.
A 30'06 vs a compound bow. The 30'06 bullet stopped in the sand, the arrow was protruding from the far side of the barrel.

A .44 magnum revovler firing two bullets of the same weight into a large deer.
One bullet is a hollow point bullet, the other is a hard cast lead semi-wadcutter. The vast majority of times, a hollow point will stop within the body cavity, the hard cast semi-wadcutter will whistle right through.

The 30-40 Krag firing an identical 180 grain soft point bullet will penetrate deeper than the same bullet fired from a 30'06.
The bullet starts with the same sectional density, but the higher velocity of the 30'06 leads to more raid expansion, the more the expansion, the lower the sectional density.</div></div>

+1

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Barikade</div><div class="ubbcode-body"> Stability also has a major role, which is often misrepresented as a product of velocity alone, fact it as one goes down the other typically goes up, to a certain point then they both go down. A less stable bullet (closer range, ergo higher velocity) may have a tendency to have a higher angle of attack, and yaw much, much earlier. Even if the bullet remains intact, flying sideways aint good gas mileage, through air or meat. </div></div>

+1


Nicely put guys cant say it better then these statements.
 
#14
Re: Higher Velocity = Lower Penetration?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: fdkay</div><div class="ubbcode-body">I don't fully disagree, but in my book sectional density and bullet construction equals penetration.

Velocity by itself does not mean more penetration, bulet weight, bullet construction, sectional density and target medium all play a role.

A frangible bullet traveling at 3200 fps will NOT penetrate as deeply as 230 grain .45 caliber hardball.

If velocity alone equaled penetration, then why does the 5.56/.223 penetrate less than the 9mm, hence the major reason for the switch from subguns to SBR's on entry teams.

No, wrap your head around this, while th e9mm will penetrate body tissue, walls and intermediate barriers better than the 5.56, the 5.56 will penetrate level III soft body armor while the 9mm won't.

The sectional density of an arrow is very high, it's velocity is not. A complete passthrough with an arrow is a very common thing.

My dad once saw a demonstration of shooting into a sand filled plastic barrel.
A 30'06 vs a compound bow. The 30'06 bullet stopped in the sand, the arrow was protruding from the far side of the barrel.

A .44 magnum revovler firing two bullets of the same weight into a large deer.
One bullet is a hollow point bullet, the other is a hard cast lead semi-wadcutter. The vast majority of times, a hollow point will stop within the body cavity, the hard cast semi-wadcutter will whistle right through.

The 30-40 Krag firing an identical 180 grain soft point bullet will penetrate deeper than the same bullet fired from a 30'06.
The bullet starts with the same sectional density, but the higher velocity of the 30'06 leads to more raid expansion, the more the expansion, the lower the sectional density. </div></div>
Right On! Sometimes real word examples shoot holes in a theory! In this case taking your time (going slower) as compared to Jumping up and annoucing the answer (going faster). The frangible bullet vs hard ball is a great example! Another one is the stability of a projectile-at what speed does it "key hole", thanks for the very well presented-and well thought out post!
 
#15
Re: Higher Velocity = Lower Penetration?

Ae454,

Sitting bored in a waiting room with my laptop so I decided to post.

It is possible that you may have heard/read that statement in regards to L.E. Urban Carbine doctrine.

If that is the case, it is true when paired with most TAP, HP and other high expansion rounds in 223/5.56.

N.T.O.A. documented such findings a few years ago using MP5 9mm, Glock 40S&W and AR/CAR.223 with expanding ammo.

In every instance the slower the bullet was going, the more sheet rock, wood, tissue was penetrated.
223s with 10-11" barrels would show more penetration than the 14.5" and 16" guns. In urban/high population density settings, that is a bad thing.

The higher velocity helps the bullet deform more on the first barrier layer. Subsequent layers or tissue depth would slow and stop the projectile in a shorter distance due to the early deformation/increase in diameter. Anytime a bullet deforms or expands, it is giving up a huge amount of energy that would have otherwise been retained for penetration.

The TAP and similar rounds are meant to be low penetration rounds that minimize the chances of exititing a dwelling or torso. Doing so has obvious implications for other team members and non-combatants. If you want more penetration as a car killer or barrier penetrator, use different rounds or weapons.

So in the context of the above ammo and weapon types, your statement is very true. In fact that has been a determining factor in many agencies choosing 14.5" or 16" carbines over the Commando or KittyCat length guns.

I sure there are a bazillion other circumstances that your statement could be addressed with but that one is very familiar to me.

FWIW.
 
#16
Re: Higher Velocity = Lower Penetration?

I tell ya what, when I get a running start all the way from the living room, step off a sleeping dog, get an accelerator from the ceiling fan and thrust point first the penetration is ALWAYS deeper than when I roll over start speeding up from one foot out. But to get MAX penetration how I does it is get a slick and slide water slide from wal mart and lay that down the hall way, at the end set up a liberator wedge lubed with KY as a ramp. Get a runnin start from the living room, hit the water slide and LAUNCH off the liberator wedge hitting terminal velocity, penetration will be exessive
 
#18
Re: Higher Velocity = Lower Penetration?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Terry Cross</div><div class="ubbcode-body">Ae454,

Sitting bored in a waiting room with my laptop so I decided to post.

It is possible that you may have heard/read that statement in regards to L.E. Urban Carbine doctrine.

If that is the case, it is true when paired with most TAP, HP and other high expansion rounds in 223/5.56.

N.T.O.A. documented such findings a few years ago using MP5 9mm, Glock 40S&W and AR/CAR.223 with expanding ammo.

In every instance the slower the bullet was going, the more sheet rock, wood, tissue was penetrated.
223s with 10-11" barrels would show more penetration than the 14.5" and 16" guns. In urban/high population density settings, that is a bad thing.

The higher velocity helps the bullet deform more on the first barrier layer. Subsequent layers or tissue depth would slow and stop the projectile in a shorter distance due to the early deformation/increase in diameter. Anytime a bullet deforms or expands, it is giving up a huge amount of energy that would have otherwise been retained for penetration.

The TAP and similar rounds are meant to be low penetration rounds that minimize the chances of exititing a dwelling or torso. Doing so has obvious implications for other team members and non-combatants. If you want more penetration as a car killer or barrier penetrator, use different rounds or weapons.

So in the context of the above ammo and weapon types, your statement is very true. In fact that has been a determining factor in many agencies choosing 14.5" or 16" carbines over the Commando or KittyCat length guns.

I sure there are a bazillion other circumstances that your statement could be addressed with but that one is very familiar to me.

FWIW.
</div></div>

I provided a link in my original post if your interested in reading it. It's a type of ammo, in context of hunting. Regardless of the context though, your post still backed up the idea.
 
#19
Re: Higher Velocity = Lower Penetration?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: VAJayJayPunisher</div><div class="ubbcode-body">I tell ya what, when I get a running start all the way from the living room, step off a sleeping dog, get an accelerator from the ceiling fan and thrust point first the penetration is ALWAYS deeper than when I roll over start speeding up from one foot out. But to get MAX penetration how I does it is get a slick and slide water slide from wal mart and lay that down the hall way, at the end set up a liberator wedge lubed with KY as a ramp. Get a runnin start from the living room, hit the water slide and LAUNCH off the liberator wedge hitting terminal velocity, penetration will be exessive </div></div>

Okay.
 
#20
Re: Higher Velocity = Lower Penetration?

So the question ultimately should be... What is the velocity that produces the maximum penetration, if all else is equal?

Let's say you had a M700, which was able to shoot, 7.62x39, .308, .30-06, and .300 Weatherby Mag rounds. Exact same gun, same location, altitude, weather, barrel length, bullet projectile, etc.

Obviously you could send rounds down range, compare and come up with rough results. But is there a way to calculate it out? I'm sure, some day there will be a formula to just number crunch it out before ever hitting the range... Wondering if anyone knows it now? How would you guys/gals find the "sweet spot" in velocity, for maximum penetration, if that was an intended goal?
 
#21
Re: Higher Velocity = Lower Penetration?

Projectile construction is probably the biggest factor. I'd like to see a 55gr .223 FMJ not penetrate as much as a 9mm FMJ. More speed=More Penetration, or More Speed=Less Penetraion. It's when talking apple to apples both statements can be true. So it would be wrong to assume that velocity alone could be the determining factor.
 
#22
Re: Higher Velocity = Lower Penetration?

Sir, good question, the FBI has actually done this testing, over and over and over. They have a set of test, from windshield, to car door, interior wall, etc., they also shoot gel blocks with cloth covers (entry end) that simulates clothes actually worn by real people, the entire set of FBI ballistic tests, and all specs can be found on line. There are others doing testing, but the FBI tests are "universal", that isn't to say other tests aren't good, it is just that when someone says their bullet/round did the following in the FBI windshield test, everyone knows what they did, and can repeat the process, in short it is a Standard. They have the budget and real professionals that do this sort of testing all the time. It really takes the wind out of the sails of those that say, "it's this by God". When FBI test show without a doubt they are wrong. It has been rightly pointed out several times by some really well written posters, that velocity and penetration are not on equal sides of the equation, the other factors must be considered. For years the old time bullet makers made bullets for "heavy and light" skinned animals, they were on to this all the way back to the big African doubles, 600 nitro express and the like.
 
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