Light and fast vs. Heavy and Slow


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MagnumDweeb
February 16, 2010, 01:51 PM
Okay this one has been bothering me for a bit now, ran across a couple articles on how a lot of law enforcement agencies have moved their otherwise known heavy grain calibers to ligther grains in the interests of high velocities. One report was of a LEO using a .40 180 grain JHP of some variety that over penetrated and harmed an innocent. After a battery of tests in other calibers and makes they decided on a .40 165 grain JHP +P. As I understand it the extra velocity helped the projectile expand so subsequently lose more momentum inside the perps and thus reduce the chance of an over penetration. While the velocity was greater, the inertia was less because of the reduced weight and surface drag of the better expanded projectile. To me this means that the round did more damage while inside the perp while either not leaving the body or if did leave the body, not with a lot of energy to do any serious harm. The same thing the article said was realized with the .45 ACP.

So if I'm understanding this right, the greater surface area, and lighter weight JHP projectile,while pushed at a high velocity is less likely to overpenetrate than a heavier round JHP because of the heavier rounds momentum.

As I understood it, when it came to SD rounds your choices ought to be light and fast, or heavy and slow. If you wanted a .45 ACP you went with JHPs that were 200-230 grain and didn't go beyond 900fps. If you wanted a .357 magnum you wanted a 125 grain JHP that did at least 1200fps. Granted I shoot Pow R' Ball and light weight high velocity JHPs already but I was just curious if anyone else held the consensus.

And then one that has me going is the reverse. Another poster, Louisianaman, has been kind enough to share his experience with a 200 grain .38 S&W and his findings on penetration which seem quite good.

Does a heavier but slower round put extra pressure on a gun. Would reducing the velocity of a .44 magnum (200 grains at 1200fps) in the interest of a heavier round (350 grains at 900fps) cause a great deal of excess pressure on gun as to harm the gun. It's just bugging me and my Google skill has been lacking on the findings. I know a gentleman who makes his own molds and molds for his friends for casting, I recently got into casting and I want to play around a little with some high grain low velocity loads out of my Ruger SBH .44 magnum. The guy told me he could do a whatever size and weight and wanted(if I was willing to wait a few weeks) in a HPSWC, RNHP, FPHP(flat point hollow point). I've got a couple hundred pounds of lead sitting about and this weekend I plan to make a few loads for the Ruger SBH in 'cowboy' loads.

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481
February 16, 2010, 02:26 PM
Hell, I want it all. Make mine "heavy and fast".

After satisfactory bullet placement, I have four criteria that my defense ammo must satisfy:

1. Penetration
2. Penetration
3. Expansion
4. Penetration

mordechaianiliewicz
February 16, 2010, 02:52 PM
Well, this is one of the oldest arguments running.... as for does it put extra pressure on the gun? Just depends. The only way to know if it does is to measure the actual CUP pressures.

Truth is, whether light and fast, or heavy and slow, you can put alot of pressure on the gun depending on powder charges.

James T Thomas
February 16, 2010, 04:05 PM
The problem is that indeed, the light, fast, and expanding ammo may not overpenetrate. It may dump it's energy into tissue destruction.
And then it may also not give enough penetration.
Sometimes great tissue destruction does not quell an assailant; depending on what tissue is disrupted.

Please just ignore the cheerleaders for placement, placement, placement.
-Of course! Hits in the vitals such as spinal column, brain, etc. will be rapidly fatal and decisive. Regardless of caliber.

But what about the off placement rounds, if you have them? And you might.

Consider if you have the minimum .380 for example. If it expands it uses the lead in the front to open and deform and as it does so, in continuing, it consumes the lead progressively along the bullet to the end. It is stubby.
So, what you have is a Nickel shaped slug. Not a dart. If the expansion occurs rapidly, that slug may come to a rapid halt in penetrating, and you have inflicted a shallow, but damaging wound.
Now your assailant is still firing at you and the innocent by standers are in jeopardy from his rounds, rather than any over penetrating rounds from you.
Do you risk his fussilage straying into the public, or your shots at him with the chance of over penetration? And your concern for their welfare by knowing what lies behind this perp? Who is placing the public at risk?

For this reason I like the rounds that have shank; that can give you that
needed sectional density to reach the spine and deep innards.
I will intensely watch whom is behind that shooter, and make my aimed shots.

Most of the law enforcement administrators have reached that position by playing the game and their concern is political -first, not effectiveness
of survival for the rank and file. I had a sherrif friend tell me his .40 rounds were designed to penetrate no more than three inches, and he felt that was a good thing.
I suppose, although he didn't say so, that he percieved that he could just hit that enemy multiple times if he needed to. May be.

As to the developed pressure, I don't know.
But powder selection has an effect. Slow versus fast burning, as well as bullet weight and powder quantity.

MagnumDweeb
February 16, 2010, 05:20 PM
Okay, dumb question then, how do I calculate the CUP then. Any formulas or online calculators I can use. The idea of heavy projectiles moved at low velocities fascinates me for some reason, might go back to my college days in rugbee.

Will a heavy projectile setup as a HP expand well at low velocities if it's a cast projectile without a jacket. I think this would be viable in a revolver because of a lack of feeding issues.

James T Thomas
February 17, 2010, 05:24 PM
The classic .357, 125 grain round at 1200 fps was a "meplat" soft point; lead, semi jacketed.
It did expand well most of the time. The early ones had 1400 fps.
Perhaps some reader knows the hardness for such soft points.

It seems to be; concensus, that 1100 fps is the minumum for HP expansion -the newest tech designs, though a few are even lower than that.
For consistency, the bullet weight which provides the sectional density required is a factor. That is the lighter your projectile, the more velocity is required. There is a direct correspondence to the bullet weight selected and it's velocity. For the soft points then, back to the standard, 1200.

CUP is measured with devices usually in a laboratory.
I don't know the mathematics for it. Sorry.

kludge
February 17, 2010, 05:34 PM
The classic .357, 125 grain round at 1200 fps was a "meplat" soft point; lead, semi jacketed.
It did expand well most of the time. The early ones had 1400 fps.

I still get 1425 fps from Remington 125gr SJHP from a 4" barrel. (S&W M19-3)

NG VI
February 17, 2010, 05:42 PM
It doesn't take 1100 feet per second to guarantee expansion, it takes proper bullet design. Golden Sabers, Ranger-Ts, HST, these and others are all more than capable of delivering textbook performance without being super-fast.

And a 125 grain at 1200 feet per second is 9mm performance, not .357 Magnum performance. Again, performance is inextricably linked to the JHP design, more than any other single factor.

NMGonzo
February 17, 2010, 07:19 PM
Heavy and fast !!!

lions
February 17, 2010, 07:53 PM
I would say medium weight and moderate speed... but that's how the 40sw got started and I don't want to go there.:neener:

PAPACHUCK
February 18, 2010, 07:57 AM
Heavy penetrates. I like penetration.

Walkalong
February 18, 2010, 07:59 AM
Shot placement. Works with both. ;)

svaz
February 18, 2010, 06:27 PM
As I understand the argument, penetration has more to do with having enough mass to punch through something then into somebody, because, frankly, our vitals just aren't that far away from the skin; and no round, no matter how light or frangible, is going to bounce off the skin.

So what is your likely scenario?

SD/HD? You probably don't want to go shooting through your walls if you have little ones or live in an apartment; if you have to, sheet rock is not that great a barrier.

If you are LE, you might have to shoot through windshields, car doors, etc.

Use the right tool for the job.

Me, I use whatever feeds reliably; if that means FMJ, I'm ok with that.

MagnumDweeb
February 18, 2010, 06:37 PM
I was trying to come up with a way to calculate the PSI or CUP of a .44 magnum round that was 400 grains pushed at 600 fps or 900 fps, and a .357 magnum 300 grain pushed at 900 fps and the pressure it would put on a gun. It was really just a self-indulgent interest and the only options it seems is to buy expensive software, there is a Hornady calculator but it won't work on my laptop or desktop for one reason or another.

I was just curious to create a SWCHP or LRNHP that was a really heavy cast round that was slow moving but heavy. In the hopes of creating a low recoil yet punishing SD round. Also the in the .44 magnum, being a .40+ caliber, the round would be a good HD round that while capable of punching human flesh, would not well escape a home. I figured heavy weight would carry the round to the vitals, the HP in the cast lead would lead to expansion, while the velocity would punch the flesh yet cause the round to lose it's momentum quickly and cause the round to 'yaw' inside the human body as the round expanded and should it leave the body, leave with minimal speed and energy incapable of well penetrating walls made up of dry-wall and plywood. Also shold the round go errant, because of it's low speed and heavy weight, it would experience severe drop after twenty yards and hopefully drop compeletely before five hundred yards. Just some self-indulgent ideas.

MachIVshooter
February 18, 2010, 06:57 PM
Heavy and fast. That's why I like 10mm. 180 grainer @ 1,400 is a hard hitting round.

James T Thomas
February 18, 2010, 07:26 PM
MagnumDweeb:

As you are still enquiring for some kind of method, perhaps some simple physics.

F= mxa The Force is the pressure on the base of those bullets:
0.164 sq.in. for the .457 base dia. of the 44, and 0.113 sq.in. for the .399 in dia. 357.

Mass of the 44; 0.00177 slugs. Sorry, but we're in the Eng. system.
And 0.00133 sl for the 300 gn. 357.

You will have to calculate the Accelerations, dependent on your barrel length
and the theoretical muzzle velocities. Perhaps go with that 900fps for both.

Now you can get a theoretical force needed to accelerate those masses to the velocity stated, with the area of the bullet bases you have.
Barrel friction has been entirely neglected here to keep it simple, as have other parameters. I don't want to get a headache!

Are you still there, Magnum Dweeb?

NG VI
February 18, 2010, 08:18 PM
MagnumDweeb I don't know about pressure, but that seems like a load style that would punch straight through a person and fly on through the rest of the house too, like a 45-70 lite or something.

Does seem like a really fun load to play around with though.

340PD
February 19, 2010, 09:59 AM
This comes from a great bullet mfg.

http://www.missouribullet.com/technical.php

Boats
February 19, 2010, 01:39 PM
As I understand the argument, penetration has more to do with having enough mass to punch through something then into somebody, because, frankly, our vitals just aren't that far away from the skin; and no round, no matter how light or frangible, is going to bounce off the skin.


Lighter rounds are going to be more deflected by bone, which everyone has in abundance in their rib cage. Between the ribs and your "chest plate" along the sternum, you are constructed a little tougher COM than you are giving credit for.

This is not to mention that clothing, particularly winter clothing, is a barrier all its own that can fill a hollow point cavity and prevent it from hydro-dynamically expanding.

Given that a bullet is likely to encounter bone in even a well placed shot on a human, and given that most of us wear clothes, even on COPS, I am firmly in the "heavy and slow" school, since heavy and fast is hard to realize in any platform I actually like.

147 grain GDHP in 9mm
158 grain GDHP in .357 Magnum
230 grain GDHP in .45ACP.

1) Shot placement.
2) Penetration.
3) Expansion.

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