Stupid gun question

O

Ocraknife

New member
I'll probably get flamed for asking this but the difference in size between the 10mm and .357 mag casing seems pretty substantial. Its my understanding that both have similar kinetic energy capabilities. How is this achieved? Are the case volumes more similar than the seem or are the powders very different?

Thanks
 
I believe it is because the 10mm is wider: great surface area for the pressure in the case to act on the bullet which off-sets the lower length of the case
 
The difference is partly because the .357 case is seldom filled to its capacity. The case was made longer than .38 Special not for greater case capacity but to prevent .357 cartridges from being used in .38 Special revolvers; for most powders, there is plenty of room left in the .357 case when the pressure limit is reached. Also, the .40/10mm case is larger in diameter than the .38/.357 case, so the ratio of case capacity to case length is greater.

Jim
 
I'll probably get flamed for asking this
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Nonsense, we discuss these things all the time. It's so much more enjoyable than discussing ninja-tactical gear and "how to respond to zombies" :p

Jim's answer is terrific but he left out one detail that helps explain... the .38 Special is H-U-G-E for what it does and as he said, the .357 Magnum is only that (long!) length to ensure it could not be stuffed in to .38 Special handguns.

At it's core, your answer really is... the 10mm was designed in the very late 70's or (effectively) developed in the 1980's, in modern time, and run a max pressure of 37,500 PSI. The .357 Magnum's long case length is only so because it was based on the .38 Special, which was developed before the turn of the century.

If the .357 Magnum and the 10mm Auto were designed around the same time and not based on any previous cartridge, the .357 Magnum would be MUCH more compact.

You also reference "similar kinetic energy capabilities" and while that is correct, it can be misleading. Always keep in mind that kinetic energy is a number, it's the product of a mathematical computation that is weighed quite heavily (almost irrationally so) on bullet velocity. This is quite easy to see when you see these silly WHIZ-BANG defense rounds that some small ammo makers advertise and sell -- they run a bullet that ends up being nearly HALF the standard weight for the caliber... and because of this, the bullet reaches blinding speeds and returns eye-popping kinetic energy numbers.

The numbers are not a lie, they are simply products of math, but they do not result in super-performing ammo. They only result in extremely oddball ammo at a high price with an eye-popping energy figure emblazoned on the product packaging.
 
All of the traditional "stopping power" formulas were based on momentum, rather than energy.
People who shot things for a living wanted big, heavy bullets.
Muzzle energy became popular when "magnum" cartridges started producing really big numbers that looked impressive.
 
I'll probably get flamed for asking this but
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Nonsense ...It's an excellent question.
It's one of those types of questions where my first answer would be," If you got into reloading, we wouldn't be having this discussion".

Handgun case volume isn't a critical factor.
It hasn't been since the black powder days.

Powder weight and burn rate are the critical factors.
Those steer the chamber pressure.
Higher chamber pressures usually result in higher velocities.
Higher velocities result in higher energy.

Double the weight of a bullet and you double it's energy.
Double the velocity of a bullet and you quadruple the energy.

Here's a simple energy calculator.
http://www.ballistics101.com/muzzle_energy_calc.php

I like this one because it leaves out things that just confuse the issue - like calibers.

Here's a link to Alliant Powder's online reloading guide.
You can browse through here and find all sorts of different bullet weights and velocities in all sorts of different calibers and plug them into the energy calculator.
http://www.alliantpowder.com/reloaders/index.aspx

Let's take a .357 mag, 125 grain Gold Dot Hollow Point.
17.5 grains of 2400 gives 1400 fps.
Energy = 544 ft pounds

10mm - 180 grain Gold Dot Hollow Point - (GDHP)
8 grains of Unique gives 1138 fps
Energy = 514 foot pounds

So, you have on round that's .357" in diameter and weighs 125 grains and a .40" diameter bullet that weighs about 30% more @ 180 grains and they have very similar energy figures.

Let's go one step beyond and throw in a .44 Rm Magnum just for grins.
The .44 Mag case is big enough to nearly swallow both the .357 and the 10 mm.
7 grains of Unique gives 899 fps using a 240 grain cast lead semi wad cutter.
Energy = 431 foot pounds
(Here's the thing. I've been reloading for roughly 40 years. I bet if we upped the charge of Unique to 8 grains, we'd be well within safe levels. I know this for a fact because some of my other manuals say it's safe)
(I also bet the velocity would jump up to right around 1000 fps)
Just for the sake of discussion, let's look at that
8 grains of Unique under a 240 grain bullet @ 1000 fps.
Energy = 533 foot pounds


So there you have three separate rounds, all having very different case capacities and all generating about the same energy levels.

The powder - 2400 for the .357 and Unique for the 10mm and .44 mag, are different. 2400 is a slow burning powder while Unique is pretty fast burning.

Unfortunately, they don't list the pressures.

W/any hope, you can start to see why energy figures, at handgun levels, have very little meaning.
A couple.three hundred feet per second one way or another can have a very profound effect on an energy figure, but, "real world" performance isn't affected in the least.

It (energy) does have a small place however if you want to do an apples to oranges comparison.
 
The .38 Special was introduced by S&W in 1902. Slightly AFTER the turn of the century.

And, yes, the case is the size it is because the round was originally developed with black powder.
 
Thank you for the insight and education. I will probably get into reloading just because I enjoy the physics and chemistry of ammo. I'd love to know more about the powders.
Do faster burning powders have a higher ratio of oxidizing agents vs slower ones?

I'd like to learn more about azides used in the primers and what makes those go bang too.

Can anyone recommend a "reloading for dummies" type of book?
 
One factor that is often not discussed is barrel length which is important when comparing 357 to 10mm. Almost all of the data you see published for magnum revolver rounds is taken with 7-8" test barrels. Most of the data for semi-auto rounds is taken with 4-5" test barrels.

If you are actually shooting 357 magnum from a 7-8" barrel it will be noticeably more powerful than best 10mm loads. From more common 4" barrels 357 mag will be noticeably less powerful than the best 10mm loads.

Some of the better loads can exceed 750 ft lbs in both using 180-200 gr bullets.
 
Double the weight of a bullet and you double it's energy.
Double the velocity of a bullet and you quadruple the energy.
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I found this very interesting. I played with the calculator to see that you're right.
 
The .38 Special was introduced by S&W in 1902. Slightly AFTER the turn of the century.
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I wasn't there but I thought the 38 spl was introduced in 1898 and the 9mm Luger came out in 1902. Both great cartridges.
 
Quote:
Double the weight of a bullet and you double it's energy.
Double the velocity of a bullet and you quadruple the energy.
I found this very interesting. I played with the calculator to see that you're right.
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LOL!
Ain't me that's right dude - that's the whole basis for what's going on and how things changed around with smokeless powders!

Black powder burns at a constant rate, whether it's confined or in the open.
That constant rate means that velocities top out at roughly 1200 fps - give or take.
By using different shapes and different coatings for the black powder, it's possible to eek out a little more - but - for all intents and purposes, black powder velocities are limited to right around sonic (speed of sound).

Since velocity is fixed, the only other way to increase energy was to add weight.
In pre-rifled days, since they shot a round ball, the only way to add weight was to increase the diameter (caliber).

The rifled barrel was a game changer in more ways than one. Once the rifled barrel came along, it became possible to increase weight by making the projectile longer instead of fatter.
A .69 caliber round ball weighs about 500 grains. (Revolutionary War)
A .58 caliber "Minnie ball" weighs about 470 to 500 grains. (Civil War)
A .45 caliber .45/70 Gvt bullet used in a "Trapdoor" weighed about 500 grains (Spanish American War)
((pardon me for switching over to long arms for this - - it's just easier))

So, as you can see from the link to energy calculations in my post above, despite these three "classic American military" calibers all being different sizes - - they all have nearly the exact same energy - since velocity is fixed.

Once smokeless came along and the velocity increased, the need for larger heavier bullets went down.
Somewhat......
Again, energy figures only go so far until you run headlong into the real world.
A .30 caliber 150 grain bullet @ 2500 fps has a lot more energy than any of the above, but, when it comes to harvesting game, the big thumpers have it all over the .30 caliber - - IF - -the .30 caliber doesn't expand in a controlled manner.

Do faster burning powders have a higher ratio of oxidizing agents vs slower ones?
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Good question - - beats me. I don't know for sure.
You might want to ask that over in the reloading forum here.
I do know that there are many types of smokeless propellant and they use numerous coatings and shapes of the powders to alter the burn rates.

Any reloading manual is an excellent source of all kinds of information.
Lyman will be slanted more towards lead bullets and loading for lead bullets.
Hornady is a decent mix of lead and jacketed.

The loading manuals are updated on a regular basis & older out of date ones can be picked up pretty cheap.
A lot of the data in the older manuals is still valid.
 
And wasn't the 38 special made longer than 38 S&W or some other more ancient black powder round so that it couldn't fit into their chambers?

I think that the 357 and 44 magnum both have unnecessarily long cases because the "original" 38 and 44 rounds were black powder, which takes up more room. And each time a more powerful 38 or 44 round was developed, it was made longer than the previous round so that it wouldn't fit into the older guns and blow them up. So now we have these enormously long 357 and 44 magnum cases.

Or something like that. I am not a reloader and might be misunderstanding.
 
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So now we have these enormously long 357 and 44 magnum cases not even nearly full of propellant.
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I don't know what y'all are loading in yours, but I guarantee you that mine are full and most of the time it is compressed.

I even load compressed in the 9mm. And, all are within specs and not overpressured.
 
Always keep in mind that kinetic energy is a number, it's the product of a mathematical computation that is weighed quite heavily (almost irrationally so) on bullet velocity.
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While it is calculated using a mathematical computation and it is quantified by a specific number, kinetic energy is not merely the invention of someone who thought it would be interesting to come up with a measure of projectile performance that emphasizes velocity.

Kinetic energy is an experimentally verified scientific quantity which is a measure of a moving object's potential to do work.

It is not, by any means, the end-all-be-all when it comes to quantifying the performance of a projectile as there are many, many reasons why a projectile may not do as much work on the target medium as it has the theoretical potential to do. In fact, trying to boil the performance of a projectile down to a single number (regardless of how it is calculated) is not a productive endeavor.

That said, kinetic energy is one piece of a large and complicated puzzle in the sense that if a projectile doesn't start out with sufficient potential to do what is desired, there's no way to make up for it in other ways. It is a mistake to either over-emphasize or under-emphasize kinetic energy when discussing terminal performance.
 
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