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04-12-2009, 11:14 PM
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Folks: I have a chronograph, so I can measure velocity. Knowing that & the bullet weight, how do you determine foot pounds of energy? Hopefully, there's a relatively easy formula a non-science major may use.
Thanks, Hang-Fire Hank
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04-12-2009, 11:14 PM
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Member
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Join Date: Mar 2009
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Folks: I have a chronograph, so I can measure velocity. Knowing that & the bullet weight, how do you determine foot pounds of energy? Hopefully, there's a relatively easy formula a non-science major may use.
Thanks, Hang-Fire Hank
NRA Life Benefactor
USAF Veteran
AZ Rifle/Pistol Life
CA Rifle/Pistol Life
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04-12-2009, 11:27 PM
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E = m v x v
Energy = mass times velocity squared
avoidupois units:
Ft-Lbs energy equals bullet wt (grains) divided by 7000 x velocity (fps) squared
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04-12-2009, 11:33 PM
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It may be a little easier to use this calculator.
http://www.handloads.com/calc/quick.asp
It also calculates the Taylor KO and momentum.
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04-13-2009, 01:24 AM
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E (ft*lb) = 2.221*10<sup>-6</sup> * m (grain) * V<sup>2</sup> (fps)
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9x19, 9x29R, 9x33R, 10x22
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04-13-2009, 06:53 AM
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Muzzle velocity squared, divided by 450436, times bullet weight.
For example, a 255gr bullet leaves the muzzle at 1400 feet per second:
1400 x 1400 ÷ 450436 x 255 = 1110 ft-lbs
The "450436" number corrects pounds to grains (7000 gr to a pound), and accounts for gravity (32.174 ft/sec*sec)
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04-13-2009, 10:59 PM
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Gentlemen: Thank you kindly for your info! I can "handle" several of those formulas. Very helpful! H-F Hank
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04-15-2009, 09:27 PM
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Divide the velocity by 1000 and square it, multiply that by the weight in grains, and multiply that by 2.219.
1400/1000 = 1.4(2)=1.96 x 255gr = 499.8 x 2.219 = 1,109 ft-lb
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04-16-2009, 10:13 AM
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If there's anyone out there who uses Excel to store their reloading and chrono data this formula will work to calculate muzzle energy in ft-lbs:
=(((A1*A1)*(B1/7000)/64.32))
A1 would be the column and row where velocity is posted in fps
B1 would be the column and row where bullet weight is posted in grains
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Andy
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