Impact energy VS Penetration

[crs]

Good tests and good field results.
Looks like another top of the line penetrator.
I contacted GS long ago when they and I were first getting started . Bad timing.
When I run out of NFs, I will try GS .458 450 grain.

 

[Nhoro]

Of all the bullets I've tested in wetpack media, one penetrated through both attempts at stopping it. It is the 450 GS Custom 458 FP Solid. Impact velocity of load out of the 450 Watts was approx 2150 fps to simulate a 50 yd impact. 1st attempt was with normal media of 100% water saturated phone book bundles with a 2" hard wood bone simulation placed between bundle 1&2. Complete pass through of 36" media length. I re-built the trough and lengthened it to handle 48" of saturated, bundled phone books. 2nd attempt with same wetpack/ wood bone media set up and same load was complete pass through. Both tracks were perfectly straight with the bullets exiting point forward.

I give! I believe it's safe to say, in that velocity range, that bullet has adequate penetration for any hunting situation I will ever need. Plus, getting enough phone books of the right size is not easy as the phone books in the test are a one-time-use.

Here's the bullet.
1st pic 450 GS Custom 458 FP Solid

2nd pic is of 2 bullets recovered from a bull elephant and an unfired 450 GS FP Solid. Bullet on left is an old poacher's or farmer's muzzleloader iron slug. Middle is 450 GS FP Solid from skull. Bullet on right is unfired 450 GS FP Solid. Wasn't my elephant but I was there for the process!

3rd is wetpack in trough showing set up before test shot- note the average premium controlled expanding bullet max penetration depth mark of 18"... A Frames, TSXs and the like.

4th is rear of trough showing 450 GS Custom FP Solid exit at the 48" mark.

That is some good solid FACTUAL info. in a sea of sarcasm-well done for persevering !

 

[Nhoro]

Sorry to chuck a little physics into this discussion, it has been rolling so humorously over Greta and belted cartridges and everything in between!

Energy(kinetic) is given by 1/2 mass x velocity squared. This means that if you draw a graph of energy vs penetration, you will not get a straight line. When a 500 gr bullet hits at 2150 fps it has 7228 kJ of energy. When it slows to 1900 fps, it is at 5430 kJ. So velocity decreased by 12 % and energy decreased by 25 %. So increasing velocity gives you diminishing returns. Doubling velocity will not double the penetration but will probably give you about 1/4 more penetration.

Then we add to this problem the increase in bullet deformation and instability when you increase velocity and you make that worse.

Now in reality, energy is what makes a hole in the animals vitals and we need a certain amount of energy to make that hole wide enough and deep enough. This means a certain weight of bullet and velocity to get the job done. Conventionally we do this by saying you need a certain sectional density and velocity. This combines the hole size (calibre) and the mass and the velocity to give you an energy per calibre size of hole. That is why most people state a minimum sectional density and energy.

 

[fourfive8]

458,
most interesting.
years ago I hunted pigs with various 577 muzzle loaders and pure lead minies.
I used 180 to 240 gns of 2f. (dupont in those days)
I had to give up due to the bullets riveting and not penetrating much at all on their fighting pads.
maybe I should have tried 70 to 90 gns.
it sure would have been easier to shoot.
bruce.

Yes, most likely a lot more penetration! I'd also think a 180-240 gr charge under a Minie' would start to ouch a little! About 60- 70 grains of FFg BP was considered the standard "service load" for a +/- 500 gr. 58 cal or 577 cal Minie' (US or British respectively). Looking at some of the military test results from the mid-1800s, the basic Minie' loaded to that standard service load was close to optimal ballistically, was practical and provided very substantial penetration in a tactical military context of the era.

I've thought about my test result quite a bit. I believe that it reflected a "perfect storm" of terminal ballistic balance for maximum penetration for that particular projectile. Nothing at all planned, just a big surprise. Any slower and the penetration would have been less, as momentum would have been less. Any faster and the kinetic energy component would have started to severely flatten the nose on this soft, pure lead bullet, limiting penetration because of greater frontal resistance.

I also think there is some extrapolation of results to be had here. Generalized yes, but nonetheless valid. "Over cook" a bullet, especially a bullet of frangible construction and there likely will be an inverse relationship between penetration and velocity.

Here's an unfired, hollow base, 730 gr 69 cal Minie' next to the same Minie' recovered after testing.

 

[Forrest Halley]

I've thought about my test result quite a bit. I believe that it reflected a "perfect storm" of terminal ballistic balance for maximum penetration for that particular projectile. Nothing at all planned, just a big surprise. Any slower and the penetration would have been less, as momentum would have been less. Any faster and the kinetic energy component would have started to severely flatten the nose on this soft, pure lead bullet, limiting penetration because of greater frontal resistance.

I also think there is some extrapolation of results to be had here. Generalized yes, but nonetheless valid. "Over cook" a bullet, especially a bullet of frangible construction and there likely will be an inverse relationship between penetration and velocity.

I think you have nailed it. Perfectly tailored the velocity of the load to the composition of the projectile. Kinda makes me want a .58 carbine now...

 

[fourfive8]

I think you have nailed it. Perfectly tailored the velocity of the load to the composition of the projectile. Kinda makes me want a .58 carbine now...

Yes, a carbine would be the "bee's knees" for a nice handing muzzleloader for hunting. I have an original P53 carbine that was unmercifully beat up on the outside but is near pristine on the inside. Shoots extremely well with a 577 Minié and standard charge. Not much vel is lost because of the short barrel- normal for BP ballistics. No doubt it would have plenty of penetration for driving a Minié through an elk at 50 yards. However as with all blackpowder arms, shooting big heavy bullets, the practical hunting range will be limited because of the iron sights and arching trajectory

Pics are of P53 carbine along with P53 musket and a couple of Miniés- normal design and the RCBS design. Either would work well. I just shoot whichever type the individual gun likes best.

 

[fourfive8]

This thread has strayed slightly from original theme of OP and could easily fit in the Muzzleloaders & Black Powder heading. However the ballistics of penetration are on point and would apply across the board.

And to be 100% historically correct for either 58 cal US Rifle Musket or 577 cal British Enfield from about 1850 -1870, one of these styles or similar would work. Left two are "3 ring" Miniés and right is British (smooth sided) Pritchett with wood base plug. All three are battlefield dropped pick-ups. The middle Minié could be considered the 58 cal version of the 69 cal Minié shown earlier in the penetration test.

 

[Bob Nelson 35Whelen]

This is an interesting subject that leads to long discussions. The sectional density parameter as it relates to potential penetration is valid only for as long as the bullet remains undeformed along its path at the ballistic terminal end of travel. Sectional Density = Mass /Diameter (squared). The other variables that are difficult to pin down, analyze and predict are spin stabilization and mass forward of aerodynamic pressure stabilization within the dense media at the terminal end. Very generally I think momentum is the parameter that best describes the penetration potential for a bullet compared to other bullets with similar SDs. But again it's not a perfectly simple comparison because so many other variables may be at play between any two bullets.

One of the buggers in trying to predict or even fully understand bullet behavior, scientifically/mathematically, is the real but mostly overlooked conflict between the concepts of kinetic energy and momentum. As it turns out energy, as defined, is usually the enemy of penetration while momentum is the friend. By definition, energy is two parted- the harder a bullet pushes on any substance, air or more dense material- doesn't matter, the harder the substance pushes back (and the results of that push back is seen in the deformation of the bullet). And that kinetic energy concept is why even a little 22 rf will leave a relatively huge crater in wet clay. While at first glance energy and momentum seem to be very closely related (or even the same) they are in reality two very different things that have to be looked at differently in the context of ballistics.

What all this means in practical terms- I dunno? other than it is interesting to think about. And sometimes you can look at bullet behavior and, at least in some small way, understand why the bullet did what it did. Or, given some parameters of design, possibly predict a behavior.

Then what's most interesting to me is actually testing a bullet in media and comparing that to what the prediction is. There are always surprises along the way. One example: I was testing a large caliber, near pure lead cast bullet at very modest impact velocity in wetpack media. The penetration was far greater than I had predicted and equalled the very best of high velocity, jacketed controlled expanding bullets.

@fourfive8
All that gobbledygook made my brain hurt. I just pick a bullet based on what others have said about it in actual field use ( not company advertising hype), load it up and go and shoot stuff. Usually works for me.
Balistics is a great study but above my pay grade. If the projectile does the job I want and gives good accuracy and velocity I'm a happy Vegemite.
Bob

 

[Bob Nelson 35Whelen]

After work I sat and cuddled my double and have come to the conclusion she is my double and I lover her none the less. A 500NE will come to me later in life I'm sure but for the next 10 or so years I'll be happy with my 416 Rigby. Thats right @IvW a 416 Rigby double rifle.

NSxx

@norfolk shooter
You and @Forrest Halley have some underlying issues that need sorting out. I prefer to cuddle my wife not my rifle.
But as my dear old dad used to say:- son guns and women have 2 things in common
If you squeeze a woman at the wrong time you end up in the shit. If you squeeze a guns trigger at the wrong time you end up in the shit.
BUT
You can get a bang out of both of them.
Bob

 

[Bob Nelson 35Whelen]

No thanks don't like genetically modified foods......

@spike.t
At least it's better than the rough end of a pineapple.
Bob

 

[Forrest Halley]

@norfolk shooter
You and @Forrest Halley have some underlying issues that need sorting out. I prefer to cuddle my wife not my rifle.
But as my dear old dad used to say:- son guns and women have 2 things in common
If you squeeze a woman at the wrong time you end up in the shit. If you squeeze a guns trigger at the wrong time you end up in the shit.
BUT
You can get a bang out of both of them.
Bob

He's a regular Couch-o-phile Bun-dee! He hunts talk shows and soap operas. "Crikey this one's a giant tear jerker! Careful, the mother series can be very defensive of her spinoffs! Shh! Quiet! We're in a prime time rating slot." Maybe we can camouflage the channel changer for ya. Rattle! Rattle! Put some .35 whelen stickers on some AAA batteries to give 'em extra power in muting commercials. Hahaha

 

[norfolk shooter]

@fourfive8
All that gobbledygook made my brain hurt. I just pick a bullet based on what others have said about it in actual field use ( not company advertising hype), load it up and go and shoot stuff. Usually works for me.
Balistics is a great study but above my pay grade. If the projectile does the job I want and gives good accuracy and velocity I'm a happy Vegemite.
Bob

Im with you mate I tend to go with peoples experience and as I hunt more and more my own. As long as the animal dont suffer im a happy hunter as the job has been done cleanly and ethically

 

[Nhoro]

I like to watch my favorite shows with mine and the wife is kind enough to let me stand it up next to the bed. I have been known on occasion to have it along on my night walks around the property, but the .375 is better suited with the firedot scope.

I like to think that if an armed burglar breaks in and does the classic hide behind the wall from the movies, my lott will hardly have slowed down when it passes through the wall. Only thing to worry about is the neighbour.