Author Topic: Foot pounds of energy  (Read 930 times)

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Offline Duster

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Foot pounds of energy
« on: August 14, 2006, 10:57:29 AM »
Does anyone know of a formula to figure foot pounds of energy for a BP handgun. Reason I am asking this is a legal handgun for hunting elk in Kentucky has to maintain at least 550 ft pounds of energy at 100 yards.

If drawn I am thinking about useing my Knight Hawkeye BP handgun. The best load I have worked up is 70 grain of P-pyro and a 240 grain serria HJC bullet in 44 cal. It is possable to go to a larger bullet but the max powder load is 70 grains.

No way I would even attempt to take a 100 yard shot with this weapon. 35 yards is my max to keep them in the black.

Offline Wolfhound

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Re: Foot pounds of energy
« Reply #1 on: August 14, 2006, 02:18:37 PM »
60 gr of fffg BP at 75 yds has 588 ft lbs per Knight data. What I have doesn't have 70 gr/240 listed. Your using 70 so you should get better velocity. Do you have the muzzle velocity for your load? With velocity and bullet weight you can figure energy. I use pointblank to figure it. It'll also figure bullet trajectory and downrange energy if you also have the b.c.

I use 60 gr of FFFG 777 in my Hawkeye. I also upgraded to the Knight Extreme ignition so I'm using a 209 primer. I get 997 at the muzzle and hold more than 550 past 100 yds.

Offline lil_hunter12

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Re: Foot pounds of energy
« Reply #2 on: August 14, 2006, 03:37:31 PM »
i had been wondering about this also because i was planning on huntin elk in kentucky this year

Offline unspellable

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Re: Foot pounds of energy
« Reply #3 on: August 15, 2006, 08:00:55 AM »
The formula is:  ke = 1/2*m*v^2  where ke = kinetic energy, m = mass, and v = velocity.  The trick is keeping the units consistent.  Mass should be in slugs and we usually speak of a ball in grains.  1 slug = 225218 grains.  So for bullet mass in grains the fromula becomes:  ke = (b*v^2)/450437  where b is the mass of the bullet in grains.

Offline long

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Re: Foot pounds of energy
« Reply #4 on: August 18, 2006, 08:03:34 AM »
velocity x velocity x bullet weight in grains / 450240

1000 fps x 1000 fps  x 158 grains weight = 159,000,000 / 450240=350,9 ft lbs

compare the results to any ballistic program or loading manual

Offline S.S.

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Re: Foot pounds of energy
« Reply #5 on: September 07, 2006, 10:16:48 AM »
Unless they change it, It is 500 FP at 100 yards in Georgia.
By looking at some of the ballistic charts, Most factory loaded
.44 magnum loads will not do this. That is quite a bit of retained
energy for a handgun! I have an old .50 cal handgun that I have used,
But I only have hunted whitetail with it. I have no doubt that it would drop
an Elk within reasonable range.   
Vir prudens non contra ventum mingit
"A wise man does not pee against the wind".