[BigSkyGuy]

importance of ballistic energy

im trying to determine at what point energy is more critical than mass. for example, shopping corbon's lineup they offer (in .45):

165gr - 1250fps/573ftlbs
185gr - 1150fps/543ftlbs
200 gr- 1050fps/490ftlbs
230 gr- 950fps/461ftlbs

as the bullet weight decreases, the energy increases but at what point does the importance of energy surpass the importance of mass? what makes for a "better" defensive round?
thanks,

 

[Prospector]

IMO your simply trading off distance for the shot as you compare the ballisticss. Lighter bullet will go further before significant droppage. If considering "defensive" round, it's doubtful you'll engage at 100 yds. I prefer "mass" for those close encounters. Lower energy of the 230gr allows penetration and goodly damage without overpenetration and likely less internal damage......just my opinion though. :tongue:

 

[gunthorp]

Energy relates to how much stored up work can be done and is based upon the mass of the projectile divided by two and its velocity squared. Momentum relates to the duration and force required to start or to stop an object and is based upon mass and simple velocity. Ammunition manufacturers use energy to describe the power of a cartridge. US Army field studies slaughtering cattle indicate that power may be more closely related to momentum. The answer may lie somewhere in the middle. The concept of stopping power adds more complexity, because target anatomy and shot placement may be more important than anything else. Firepower can be demonstrated by a .50 cal machine gun burst, but unless the target is hit, a well placed .22 would have more stopping power. In a gunfight, the successful outcome depends most upon the mindset developed by positive attitude and preparation, and skill from practicing with reliable equipment.

**This table of stopping power uses a formula favoring momentum over energy.
The formula multiplies the bullet’s base area in square inches times its weight in grains times its velocity in feet per second, then divides by an arbitrary number (1000) to get a result which can be compared easily.
*
Caliber Bore Diameter Base Weight Velocity Power
*
454 Casull .451 .1598 300 1630 78.14
44 Magnum .429 .1445 240 1400 48.55
41 Magnum .410 .1320 250 1250 41.25
*
45 ACP .451 .1598 230 850 31.24
40 Smith & Wesson .401 .1263 180 990 22.51
357 Magnum .357 .1001 158 1240 19.61
*
9mm Luger .355 .0990 124 1120 13.75
38 Special .357 .1001 158 760 12.02
380 Auto .355 .0990 95 1000 9.41
*
32 Auto .308 .0745 65 950 4.60
25 Auto .250 .0491 50 800 1.96
22 Long Rifle .220 .0380 40 900 1.37

see http://www.gunthorp.com/wounding_factors.htm

I personally stick with heavier bullets for each caliber, and practice with the equivalent weight and power of the loads I carry. But, hey, try different weights anyway. Heavier bullets offer more penetration and recoil. Be sure of your background when a skinny gangbanger tries to threaten you, but you'll appreciate the heavy bullets if you run into a 300# meth freak.

 

[Bud White]

I use Heavy bullets for Caliber also I prefer a 147 in 9mm when i carry it only exception to this is 38 i carry a 125 ... 230 in the 45..

They guys above cover this pretty well

 

[KC135]

Energy relates to how much stored up work can be done and is based upon the mass of the projectile divided by two and its velocity squared. Momentum relates to the duration and force required to start or to stop an object and is based upon mass and simple velocity. Ammunition manufacturers use energy to describe the power of a cartridge. US Army field studies slaughtering cattle indicate that power may be more closely related to momentum. The answer may lie somewhere in the middle. The concept of stopping power adds more complexity, because target anatomy and shot placement may be more important than anything else. Firepower can be demonstrated by a .50 cal machine gun burst, but unless the target is hit, a well placed .22 would have more stopping power. In a gunfight, the successful outcome depends most upon the mindset developed by positive attitude and preparation, and skill from practicing with reliable equipment.

**This table of stopping power uses a formula favoring momentum over energy.
The formula multiplies the bullet’s base area in square inches times its weight in grains times its velocity in feet per second, then divides by an arbitrary number (1000) to get a result which can be compared easily.
*
Caliber Bore Diameter Base Weight Velocity Power
*
454 Casull .451 .1598 300 1630 78.14
44 Magnum .429 .1445 240 1400 48.55
41 Magnum .410 .1320 250 1250 41.25
*
45 ACP .451 .1598 230 850 31.24
40 Smith & Wesson .401 .1263 180 990 22.51
357 Magnum .357 .1001 158 1240 19.61
*
9mm Luger .355 .0990 124 1120 13.75
38 Special .357 .1001 158 760 12.02
380 Auto .355 .0990 95 1000 9.41
*
32 Auto .308 .0745 65 950 4.60
25 Auto .250 .0491 50 800 1.96
22 Long Rifle .220 .0380 40 900 1.37

see http://www.gunthorp.com/wounding_factors.htm

I personally stick with heavier bullets for each caliber, and practice with the equivalent weight and power of the loads I carry. But, hey, try different weights anyway. Heavier bullets offer more penetration and recoil. Be sure of your background when a skinny gangbanger tries to threaten you, but you'll appreciate the heavy bullets if you run into a 300# meth freak.

Neat, but no consideration given to bullet expansion. A fast expanding bullet will have less penetration than a slow expanding or non expanding bullet regardless of projectile weight.

In a self defense bullet, you need good expansion with a penetration of 10 to 14".

Example, 44 Special 180jhp at 1200fps gives both desired expansion and penetration. Good for self defense. I am sure a 240JHP at 1400 would be much better for hunting.

 

[rocky]

I go with the heavier bullets based on more mass = more bullet after expansion.

 

[P95Carry]

The energy figure is at the muzzle - things change pretty quick after that - and then for me the momentum of the heavier bullet is preferable.

I do tho - or did - unusually for me - use the CorBon 110 +P as carry in snubby. Of course it would be fairly likely anways that an encounter would be pretty short range so - in the end - placement will still be pretty much the key factor.

 

[CP14.45]

In my opinion, using a heavy for caliber bullet is the best bet(230gr. in .45 etc). The bullet has more frontal area and mass to do more damage(if proper bullet placement is achieved). You do not use a 220 Swift to hunt buffalo, but the Swift has a lot of energy but a small bullet mass. Now I am not comparing a buffalo to a human being, but I swear they are out there(the size of the person and what they are wearing comes into play).
Just my 2 cents worth...

 

[AutoFan]

The heavier bullets retain more momentum (mass x velocity) as the larger mass component does not change, hence more penetration, all other things being equal.

On a .45, you just can't push conventional rounds fast enough to get any terminal effects advantage of the kinetic energy. The faster rounds will go further before dropping ("shoot flatter").

One advantage to the heaviest rounds is that they start out subsonic, and therefore don't have to go through the transition from supersonic to subsonic, which produces turbulence and degrades accuracy.

 

[KC135]

documentation

One advantage to the heaviest rounds is that they start out subsonic, and therefore don't have to go through the transition from supersonic to subsonic, which produces turbulence and degrades accuracy.

Please document this factor concerning handgun ammo.

Thanks.

 

[AutoFan]

Well I thought it was common enough knowledge among rifle shooters, particularly with regard to .22's. If you do a search on the internet, you can find multiple rec.guns newsgroup references. More generally, many aerodynamic texts will comment on the differences of sub vs supersonic fluid flows, formation of shock waves, "termination shock" (the region where a fluid goes from super to subsonic, also referred to as transonic), etc.

Just did another search and on Speer's website they mention the "transonic zone" and "...buffeting until true subsonic veolocities are reached."

And a paper on the Fulton Armory website discussing the change of forces on the center of gravity of a dynamically stable bullet when it goes from supersonic to subsonic.

 

[KC135]

Autofan, the book 'Understanding Ballistics' by Robert A. Rinker, is very good and does explain the 'transonic zone' pretty well.

One thing about this book..have a scientific calculator handy when you read the book.

 

[RSSZ]

Everybody's got to believe in something -------and I believe in this>>> TKO(Taylor Knockout Formula). Simply put TKO=CWV over 7000. Caliber in thousandthsXweight in grainsXvelocity in feet per second,divided by 7000. This will have you come up with a number between 25 and 40(typically). I like this because it takes into consideration the diameter of the bullet. I understand that there are other factors that aren't taken into consideration buy using this formula---BUT--- nothings perfect. This is one example of why I like the .45 round for self defense.-------------