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Old December 14, 2018, 09:27 AM   #1
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Newtonian Physics and Recoil and Energy Transfer Slug Vs Buck

Newtonian Physics is not a difficult concept to get when it comes to recoil. I know. But what I’m wondering about is when it comes to the actual transfer of energy by the slug vs buckshot (or even rifle round vs buckshot).

Does buckshot deliver actual more felt recoil to a target because of the spread? I know. We can’t have a living being go “ok that pushed me backwards more,” but it is still something that could be tested. Theoretically? No. The slug does because the buckshot would spread out. But then with the area of impact and penetration? You would get a larger area of impact and that would...if penetration is able to be reduced...transfer more energy into the target rather than through it. If that makes sense?

So basically? When it comes to energy transfer? Does buckshot actually deliver MORE or LESS to the target than a slug? Why?

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Old December 14, 2018, 11:46 AM   #2
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I'm not an expert,this is opinion.

"Energy Transfer" can be misleading. Shotgun velocity does not generally make for the sort of temp cavitation that a hi vel expanding bullet does.
Elastic tissue can recover from some degree of temp cavitation.

It might be a big,blunt slug is like throwing a big rock in a pond.

But I think what we really want is trauma. Bleeding,broken bones,and neural damage.

That's not quite the same as "energy transfer"

As far as which will have the greater effect,slug or buck, IMO,its a complex question with a lot of variables.

For some situations ,buck may have an advantage,but IMO for a broader range of reliable results I'd choose a premium slug such as a Brenneke.

Penetration is critical sometimes.

Last edited by HiBC; December 14, 2018 at 11:51 AM.
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Old December 14, 2018, 01:23 PM   #3
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I would expect more surface area with shot compared to slug so air resistance would slow the shot down so there would be less energy delivered on target.
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Old December 14, 2018, 02:43 PM   #4
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Does buckshot deliver actual more felt recoil to a target because of the spread?
Felt recoil is the wrong term for the context of the question. Felt recoil is what the shooter feels, and it is not delivered to the target.

The term you are looking for is "energy", (not recoil) expressed in ft/lbs units.

So basically? When it comes to energy transfer? Does buckshot actually deliver MORE or LESS to the target than a slug? Why?
The answer is neither, if they have the same energy to begin with, AND all buckshot pellets impact the target. Energy is a straight calculation of mass and velocity. Equal mass, and equal velocity have the same total energy, no matter if the mass is one solid lump, or a dozen smaller pieces. That's the math.

Now, going beyond the math, and introducing real world factors is what makes the difference. Assuming the slug and buckshot loads are the same mass and velocity - they might not be, but assuming they are, then the difference in energy (if any) delivered to the target will be due to any buckshot pellets that MISS the target, due to spread. (again, if any)

I would expect more surface area with shot compared to slug so air resistance would slow the shot down so there would be less energy delivered on target.
Technically this is correct, each individual buckshot ball has less mass and less inertia than a single slug. But while the difference in velocity due to air resistance slowing down the shot, at shotgun ranges, can be calculated, the practical difference is nil.

What makes more of a difference isn't the speed of the shot at impact, but the TIME of the impact, and the inertia of each individual projectile.

A slug strikes at one instant, and will all the mass concentrated in one projectile, has the greatest inertia, which affects its ability to penetrate.

SHOT travels in a column, and spreads out, so the impact is actually not the same instant for all the pellets. And each pellet is smaller and lighter than the slug, so each pellet has less individual energy and inertia than the slug, and so will penetrate less.

Think about it. One .72 caliber slug (12ga) vs 9 .32 caliber pellets (00 Buck) which do not all arrive on target at the same instant. Some of those pellets are the front of the shot column, some are at the back. The difference in time between the impact of the first and the last is small, but there is a difference. All together the shot pellets may have the same ft/lbs energy as a slug, but they aren't all striking at exactly the same instant, so its not identical.

The small difference in time of impact doesn't matter for a big game animal as much as the spread of the shot can. This is different from bird shooting.

Buckshot has a high probability of having a pellet or two or three actually missing the vital area, at longer ranges. and every pellet that doesn't hit the vital area is that much energy not delivered to the vital area.

clear as mud now??
All else being equal (and it almost never is) bigger bullets tend to work better.
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Old December 14, 2018, 02:51 PM   #5
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The base issue is both absorption of the (kinetic) energy at the target and the resulting biomechanics of the trauma caused.

If a weapon has 1,000 ft lbs of energy at the muzzle for a slug or buckshot, it also has an equal and opposite reaction, ie.; 1,000 ft lbs of recoil into whatever is on the back end of the gun.

So let's assume that the target is very close to the muzzle, and is hit by a slug or buckshot with just (about) 1,000 ft lbs of kinetic energy.

If the slug or buckshot is absorbed and totally remains within the body it hits (none passed through), then that body absorbed the same amount of energy for either.

Conversely, a lesser mass boat tail round with 1,000 ft lbs of energy is traveling much faster than the slug or buckshot, and may pass through the body, leaving significantly less energy in the body, but causing significantly more damage because of the shockwave, by rupturing more veins and arteries and result in more lethality. Or may not.

All also depend on shot placement. A slug that penetrates into the heart may be an instant kill, while a chest full of buckshot may be painful but not lethal.

Bottom line, it depends on many more factors than just energy, shot placement, projectile and other factors.
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