Can you compare these two loads?

S

Super-Dave

New member
Suppose you have two different loads

Bullet A: 125 grains at 1400 fps

Bullet B: 180 grain at 972 fps

If both bullets were the same caliber and fmj, would they penetrate to equal distance?
 
If both bullets were the same caliber and fmj, would they penetrate to equal distance?
Click to expand...

Maybe.

Bullet penetration tends to increase up to about 1200 fps. Above that, the penetration can start to deteriorate...depending on the material being penetrated.

Water, and therfore water based solids react to different velocities differently. Much the same way a water skier rises out of the water more and more 'till (s)he reaches around 42 miles per hour. At that point, water becomes a solid for a skier.

Bullets are different, of course, but it seems that the farther above ~1200 fps a bullet gets, the harder the water or water based solid gets.

So...

You bullet at 1400 fps is 200 fps above that ~1200 fps mark, and the 972 fps bullet is 228 fps under that ~1200 fps that seems to give the maximum penetration.

That said, only testing would tell you for sure.

Now, with that said,

While penetration may be similar, a water based mass (milk jug full of water, small animal, etc) will most likely react more violently to the bullet's impact. When that water base gets harder for the higher velocity bullet, it also reacts more violently to enerty transfered to it from an outside force.

So the 972 fps bullet might slip through fairly easily, while the 1400 fps bullet will penetrate what becomes a more solid mass due to the higher velocity, and the damage can be more dramatic...

even if penetration depth remains the same.

Daryl
 
For what it might be worth: Your Load A calculates to 544 ft.lbs. of muzzle energy, while your Load B calculates to 378 ft.lbs.

The penetration of a bullet into target material depends on a zillion factors, of which three dominate: the nature of the target material, the design and construction of the bullet, and the bullet's energy at point of entry. All other factors held equal (an almost impossible caveat with bullets of different weights), the slug with the greater energy at entry has the greater potential for penetration into the target -- assuming neither bullet exits.

All of the foregoing theory notwithstanding, I'm uncertain what the practical implications of the question are.
 
I though all that mattered was force or momentum if you are talking about the same caliber and bullet construction. I thought Energy would be irrelevant.
 
As the velocity of a projectile climbs, the violence of its interaction with whatever target it strikes increases.

A high velocity projectile does a lot of things that are increased greatly above what occurs with a slow projectile. Upon impact, the compression and shock wave that are created are more energetic, as well as the heat and friction as it goes through, and the violence of displacing material is much higher.

What this means, is that high velocity projectiles shed enormous amounts of their energy unnecessarily in the violent impact, and that energy is not left alone to do the job of penetration.

Consider a very small meteorite, and a satellite. The things travel at velocities that top hundreds of thousands of fps, and even a grain of sand striking a piece of equipment can cause such a ghastly shock wave that it can damage it beyond functioning.

The military uses tank rounds that are essentially nothing but crowbars made of depleted uranium, loaded into sabots, and fired a extreme velocities at tanks. The impact of this high velocity bar causes a greater explosion that high explosives can. It is the extreme velocity that causes this.
 
I suspect that in some cases, really high energy loads like a maxed-out 357Mangle'em 125gr doing 1,600fps is going to put an "extra special hurt on", esp. if it hits and shatters bone.
 
Suppose you have two different loads

Bullet A: 125 grains at 1400 fps

Bullet B: 180 grain at 972 fps

If both bullets were the same caliber and fmj, would they penetrate to equal distance?
Click to expand...

Actually this is a good question. Unfortunately it's posed abstractly.

If both bullets are the same caliber but different weights and traveling at different velocities, with bullets that are of identical or similar construction, major factors determining depth of penetration will be a)what you hit with the bullet, the type of material. b) how far from the shooter the bullet travels before it hits and c) what caliber the round is (the dia. of the round becomes a factor here).

tipoc
 
I though all that mattered was force or momentum if you are talking about the same caliber and bullet construction. I thought Energy would be irrelevant.
Click to expand...

You thought wrong.

For the bullet weights and velocities you gave only one widely available round will fit the bill and that is the .357 Magnum. So lets be less abstract and useless and look at that.

Kinetic energy is measured in foot pounds. A foot pound of energy is a measure of how much work it takes to raise a one pound weight one foot off the ground. This is literally what it means. It is a measure of the ability to do work. So when we read that some loads have 350 ft. pds of energy at the muzzle what we are saying is that the bullet, at the point that it leaves the barrel, has enough energy available to it to raise a one pound weight 350 feet off the ground or a 350 pound weight one foot off the ground. This does not tell you how "powerful" a round is or how hard it hits or how effective it is. It does let you know how much potential it has to do work. All bullets do work and shed energy as they do. The lighter, faster bullets shed energy at a higher rate then do the heavier rounds even in the same caliber.

So, for example, the slowest 180 gr. load I could find out there is one from Federal that sends a 180 gr. pill down range at 1090 fps with 475 ft. pds of energy at the muzzle. At 100 yards it has slowed to 890 fps but still has 320 ft.pds. of energy. This is plenty of energy for a good hit on a deer and with a 180 gr. lead semi wad cutter bullet would be a bone breaker and good for a quartering shot. A heavier bullet would be better still but than I'd go up in caliber to the 44 Special for a more effective killer at 100 yards, if it was me.

Now Federal also makes a 125 gr. load at 1450 fps and 580 ft. lbs of energy available at the muzzle. At 100 yards the velocity is 1100 fps, a loss of 350 fps, and the energy has dropped to 335 ft lbs of energy. Still a good amount of energy but the lighter bullet weight now works against it as it must shed it's energy faster if it hopes to penetrate as deeply as the heavier load. While it can still be a very good penetrater at this velocity, if full metal jacket a very good penetrater, it is not so good against game as the heavier round at this range as it delivers less shock.

At a different range things may be different. And against a different material they will be quite different.

The more concrete you get the easier it is to get a reasonable answer that is not full of random speculation and the more real things one can learn.

tipoc

tipoc
 
FMJ what? RN, FN, FP, TC, SWC, WC, what, give us a hint? FMJ is not a bullet shape.

Pointy bullets I give the nod to high velocity, blunt bullets I give the nod to heavy bullet.
 
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