Question on .45 ballistics

[Toppers]

I was looking at the link for blazer brass in .45. According to their site, .40 S&W has higher numbers like ft/lbs. energy. I thought .45 had more than the .40? I know it's the slowest bullet, but I always thought it had the highest muzzle energy.

http://www.blazer-ammo.com/blazer_brass.aspx

[eightmillimeter]

It looks like Speer loads all of their 45ACP 230 Practice ammo (Blazer, Blazer Brass, and Lawman) to 830 fps which is a little slower than other loads. They list their 230gr Gold Dot at 890fps and 405 ft-lbs energy which tops the 40's energy. 890 May be the more realistic figure for 230 out of a 5 inch test barrel these days. That said and if I remember the physics right the formula for energy is 1/2Mass x Velocity squared. That said it would look like velocity has the biggest influence on energy, and then with the added mass the "average" 45 will have more energy from the "average" 40. It's all relative. If I'm not on the right track here somebody please correct me.

[Mercmar]

Many lightweight bullets fired from, from example, .40 Super, have considerably more muzzle energy than do .45ACPs. .45ACP is a pretty low-muzzle-energy round.

[Toppers]

So, I thought ft.lb energy had a direct correlation to stopping power. This suggests that a .40 has more stopping power? I mean getting hit with either one is going to suck, but..

[Noah Mercy]

Many 40 S&W loads outstrip the 45 ACP based on lb/ft, but a foot pound never stopped crap. The bullet is what does the work, and while lb/ft can be a rough predictor of stopping power, it is not the be-all end-all. If that were the case, a 22-250 would be better on grizzly bears than a 45/70. The foot pound equation gives inordinate weight to velocity and ignores bullet diameter, construction (shape, material, and weight/ sectional density), and momentum. It doesn't take into consideration whether the bullet is designed for an "early" or "late" release of energy. It ignores penetration and secondary wounding characteristics (does the bullet have sharp exposed "petals" that add a cutting mechanism to the projectile?).

In actual street shootings, the 125 grain 357 Magnum, 155 grain 40 S&W, and 200 & 230 grain 45 ACP have proven to be the most reliable rounds at stopping a bad guy, regardless of his mental or physical state. All rate between 92 and 95 percent one-shot stops with solid thoracic hits.

Ignore the lb/ft hype...a well-placed 40 or 45 will end a fight and the bad guy isn't going to notice a few pounds of kinetic energy one way or the other.

[Myk9noseknows]

Think of it this way regarding velocity and energy.

Get hit with a golf ball at 100mph (.40)

Get hit with a brick at 75mph (.45)

This is a generic comparison but suppose the golf ball (.40) had a higher transfer of energy, the brick has lower energy, but because of it's greater mass, it has more "knockdown" power.

It's the same with a 9mm and a .22lr, they have roughly the same energy, but because the .22 is 35 grains and the 9mm is 115 grains, the 9mm has more "punch"

[eightmillimeter]

Originally Posted by Toppers

So, I thought ft.lb energy had a direct correlation to stopping power. This suggests that a .40 has more stopping power? I mean getting hit with either one is going to suck, but..

Many people argue that very point and some data suggests that. Higher velocity with the same mass of a bullet will always produce more energy...however kinetic energy is a scientific measurement of a moving object's ABILITY to do work on another object. That in mind, it doesn't mean that higher velocity is always better. Modern self defense bullets are designed around the calibers to provide the best terminal performance under certain circumstances. Two identical bullets fired at the same velocity at the same target, the first doesn't expand, less energy transfer, less damage, more penetration. The second expands, more energy transfer, more damage, less penetration. The "notion" of "stopping power" depends on too many variables to just go by caliber or muzzle energy alone, one has to look at the whole picture to get the best idea; even then if the circumstances change the outcome can still be different. The 40 and 45 are both capable of putting a target down under a wide range of conditions and all the reports verify this. This day and age I find it easier to just get whatever you want. If you want a 45 make it so. If you want a 40 go for it. Only hits count when you need stopping power...ANY bullet that hits the right spot has stopping power. The rest is insurance.

[eightmillimeter]

Originally Posted by Myk9noseknows

It's the same with a 9mm and a .22lr, they have roughly the same energy, but because the .22 is 35 grains and the 9mm is 115 grains, the 9mm has more "punch"

I was with you until that. Not saying it's incorrect but explain what you mean by "roughly" the same energy please.

[Sirius1963]

Originally Posted by Toppers

So, I thought ft.lb energy had a direct correlation to stopping power. This suggests that a .40 has more stopping power? I mean getting hit with either one is going to suck, but..

Kinetic Energy is calculated as:

KE = 1/2 mv2 for example,
m = 185gr
v = 1150fps
Energy = 543.24ft-lbs

Stopping power is calculated as ... ummm Anybody?

Does "stopping power" have a formula?

[Sirius1963]

Originally Posted by eightmillimeter

I was with you until that. Not saying it's incorrect but explain what you mean by "roughly" the same energy please.

I agree... according to my calculations

.22
31 gr bullet
1430 fps (found this on some website)
= 140 ft-lb of energy

9mm
115 gr bullet
would have to go only 750 fps
= 143 ft-lb of energy

If you are only getting 750 fps out of your 9mm, you need new loads!