I need some info on ft lbs and recoil.

[5ptdeerhunter]

I am doing a paper and I need to know some information about muzzle energy and ft lbs and for some handgun calibers. I mainly need .357, 9mm, .40S&W, and .45. I am comparing the different calibers and would like to know the differnence in recoil as well.

If anyone has a chart or something like it, that would be great.

Thank you for you time,

Michael

 

[grimjaw]

Chuck Hawks has some numbers on his site.

jmm

 

[R. W. Simms]

You can calculate it very easily yourself as long as you know the bullet weight and velocity. The formula is 1/2 the mass times the square of the velocity.

Take the weight of the bullet in grains and divide that by 7,000 to get pounds. Divide that number by 32.2 to get slugs (slugs is mass, pounds is force). Multiply this number by the velocity, then multiply it by the velocity again. Divide the final number by 2 and you have the muzzle energy in foot-pounds.

Example 1: A .45 ACP uses a 230 grain bullet and travels 850 fps.

230/7,000 = .033
.033/32.2 = .001
.001 X 850 X 850 = 723
723/2 = 362 ft-lbs

Example 2: A .38 Special uses a 158 grain bullet and travels 750 fps.

158/7,000 = .023
.023/32.2 = .0007
.0007 X 750 X 750 = 394
394/2 = 197 ft-lbs

It'll work for any cartridge as long as the bullet weight is in grains and the velocity is in feet per second. Good luck with your paper.

-Bob

 

[P95Carry]

The Chuck Hawks suggestion is good - plenty of useful info.

Bob - for me I do find this following version simple -

Take velocity - square it - multiply by bullet weight in grains and then divide by 450356 (that number is fractionally off - just happen to remember it and error is insignificant).

So if we had a 45 acp 230 grainer at 800 fps -

800^2 = 640,000
640,000 x 230 = 147,200,000

Finally - 147,200,000/450,356 = 326.85 ft lbs.


There is a simple formula somewhere re recoil too - but forget it! All it does in essence is relate the relatively small bullet mass and vel to the relatively large mass of the gun - and return a perceived recoil poundage. The gun of course is a large inertial mass and so takes longer to accelerate than the bullet, plus forces are distributed over a good area - whether hand or shoulder - thus pressure (force per unit area) is well dispersed.

 

[MCgunner]

I am doing a paper and I need to know some information about muzzle energy and ft lbs and for some handgun calibers. I mainly need .357, 9mm, .40S&W, and .45. I am comparing the different calibers and would like to know the differnence in recoil as well.

Some personal thoughts on this subject. While the .357 factory loads run around 550 ft lbs from a 4-6" barrel, I can get 750 out of a good handload, easily. While .45ACP runs around 350 ft lbs, I can hand load it to around 500 ft lbs using a heavy recoil spring in the gun. 9mm, I regularly load to 440 ft lbs out of a 5" gun, still making 400 ft lbs out of a 3" compact. Standard factory loads, normal pressure, are around 350 ft lbs. I have no .40, so haven't played with it. Advertised energies for the lighter bullets are over 500 ft lbs, though. It's a hot caliber. I probably ought to acquire one, but I don't figure I can to anything with the .40 I can't do with my .45ACP

There are some loads in .357 from buffalo bore that I need to check out for myself, better than I can get from my handloads. They're pushing 900 ft lbs from a revolver! I'm in a wait and see mode on those loads until I can acquire some to shoot over my Chrony. Sounds too good to be true, yet I've seen 'em tested in an article at Gunblast.com.

But, depending on load, your mileage may vary. Different loads in a given caliber vary from mild to wild from manufacturer to manufacturer.

Now, you say ".45" and I just assumed you meant .45ACP. .45 Colt can be loaded to .44 mag levels and even the standard stuff is around 400+ ft lbs. .45 Colt is one of my favorite revolver cartridges.

 

[telomerase]

energy doesn't equal recoil

The other guys have given you the Newton formula for kinetic energy, which is good enough for the low-tech weapons our owners allow us. However, this tells you nothing about recoil. A light projectile at a high velocity will give more energy for the same recoil than a heavy one at a low velocity. The extreme example would be a laser; you could fire a laser that could cut a tank in half and not feel the recoil at all. (Reflections would be another matter...)

To figure recoil of an unsupported gun:

Calculate the bullet (and powder gas) momentum, not energy. (Momentum = mass times velocity).

Action = reaction, so the momentum of the gun = the momentum of the bullet. Find the velocity of the gun.

Now plug the mass and velocity of the gun into the kinetic energy formula, and you have the recoil energy of the unsupported gun. (And this is why you should hold the gun tightly; the more mass of your hand and arm is added to the mass of the gun, the less the recoil energy).

 

[lycanthrope]

I sent an automatic recoil calculator to you through your posted e mail.