How much energy in ft lbs ?

[Bob72]

I am curious...how much energy in ft lbs is necessary for a thru the shoulder, heart/lung shot with a white tail deer. Second would be a neck shot at the base. I ask because there is a certain point beyond which I won't even try a shot if I can't get a clean kill. Thank you once again THR contributors.

 

[LoonWulf]

What round are we talking about? 12-1400ft-lbs is offten considered minimum, but that is honestly a rather poor indicator of performance (penetration or otherwise). There are too many variables to rely on enegy alone as a criteria for shoot or dont shoot.

 

[jmr40]

Conventional wisdom is 1000 ft lbs for deer, or black bear, 1500 for elk, moose or large bear, but those numbers are not written in stone. What you want is enough penetration to get the job done, and different weapons, bullets accomplish this in diffeent ways.

The above figures are fairly accurate with most rifles, and bullets, but some rounds, shooting heavy, slow bullets such as muzzle loading rifles, shotgun slugs, 45-70, 44 mag etc will still give you plenty of penetration with much lower energy numbers. Same with arrows shot from bows.

Bullet construction also comes into play. Some of the newer solid copper bullets give more penetration than conventional bullets at the same energy levels.

With modern hunting rounds, 30-06, 270 etc. I've about concuded that impact velocity is probaly a better predictor than energy numbers. Most bullet manufacturers list recommended a maximum and minimum impact velocity. If the bullet impacts game too fast it will blow up and not penetrate enough. Too slow and it will not expand and will cause too little damage. With most rounds the minimum impact speeds are around 1600-2000 fps depending on the exact bullet. Look at a ballistics chart and find the range where your chosen bullet drops below around 1800 fps and that is probably the max effective range for that bullet.

 

[scythefwd]

A .30-30 will do it.. and they have what 1300 ft lbs.. I can't think of many legal firearms in VA (.23 or larger caliber) that wont do it.. the subsonic stuff is about it.

 

[Big Bad Bob]

Craig Boddington states that 1000ft/lb at the point of impact is the minimum for an ethical clean kill on white tail.

 

[scythefwd]

big.. so the 357 mag, the 44mag aren't ethical?

 

[Cosmoline]

... or a roundball shooting smoke pole either, apparently. But like a bumblebee that doesn't know it can't fly, the roundballs don't know they can't perforate a whitetail.

 

[scythefwd]

cosmo.. depending on load.. those round balls are making 1000 ft lbs.

 

[jmr40]

Boddingtons numbers are reasonable for modern high velocity common hunting rounds. As has already been stated different bullets play by different rules. Nothing wrong with using energy numbers to compare various chamberings as long as you are comparing comparable rounds. If you compare the energy numbers of rounds such as 444, 45-70, 44 mag etc. then those numbers will give a fairly accuate prediction of performance. Same when you compare 30-06, 308, 270 etc. But if you start using energy numbers to compare a 270 to a 45-70 then they are less meaningful.

 

[Jesse 8]

False. On the .44 anyway. Heard second hand that a .44 to a doe at 55 yards almost blew her over(from my uncle about his dad, not just from some gun counter guru) out of a Winchester levergun. And she was a mule deer. .44 mag out to a hundred yards will be plenty powerful enough for a clean kill

 

[Big Bad Bob]

its not an exact science about how many ft/lbs is needed, but the goal should always be to make clean ethical kills. Boddington isnt the Almighty at this science but his writings provide alot of good data to back up his assertions.

That being said my .44 magnum 240 grain, 300 grain, and 375 grain hard casts all range in ft/lbs from 1250 to 1500 at the muzzle and under 100 yards still retain the effective amount of energy for a clean kill. I slayed a buck at about 70-75 yards last year with 240 grain JHP, and it performed but it did not exit. We will see what the hard casts do this year.

 

[adelbridge]

I had to dispatch a 150 lb buck with a knife and it didnt take much force. I have also hunted hogs with a knife and where you put the knife could be the difference between 15 lbs or 40 lbs of hand force. A 9mm will double lung a deer and exit very easily within 30 yards generating 400 ft lbs at the muzzle. An average compound bow will pass an arrow clean through a deer with 95 ft lbs and a lot more friction than a little bullet. The thoracic region on a deer is mostly hollow space and very little tendon and muscle tissue. Your biggest obstacle are the ribs and anything center fire should pass through at least one side of the rib cage. The lungs themselves are spongy and wont provide any kind of serious barrier. If you can deflate both lungs nothing is going to survive. A broadside shot with a .380 putting out 300 terminal ft lbs will be lethal more often than not. Quartering away or towards can contract and compress bone and tissue in which case more terminal energy is necessary. The other issue is lower energy levels dont always create a good blood source for tracking. Lower energy levels dont often drop deer in their tracks despite being a lethal shot. Combine lower blood loss and longer tracking and you may never find your deer.

 

[Texan Scott]

The problem with kinetic energy as a primary criterion is that a gun is not a directed kinetic energy weapon... it's a directed PROJECTILE weapon.
Kinetic energy = 1/2 mass * velocity SQUARED; energy increases PROPORTIONALLY as per mass, but EXPONENTIALLY as per velocity.
SO, a 55 gr .243 is SCREAMING fast, and has HUGE initial KE, BUT it has very low mass - that's why it accelerates quickly, but also why it will DECELERATE quickly in tissue- and it loses kinetic energy EXPONENTIALLY as is slows.

Slow, heavy bullets may not look 'sexy' on paper, but they take large game consistantly and well. I'd rather have a .30-30 than a .243 for hogs, any day.

 

[RPRNY]

^ Tex has got it. Look at a 12 ga shotgun slug. At 50 yards many are already skating bellow the 1000 ft/lbs level, yet a good hard Brenekke slug will penetrate and put down deer at 750 ft/lbs whereas a Foster might just cause a nasty surface wound. Velocity and kinetic energy are only parts of the equation. As someone above pointed out, the 30-30 has put more meat on the table than any other round, slow as it is.

Again, as noted above, velocity and energy are indicative in discussing like rounds, but bullet construction is core pillar of any such discussion. An insufficiently robust bullet arriving at peak terminal velocity/energy from a 270 will surface shatter, leaving a nasty wound but a running deer. Whereas the Sandyhook trials at the end of the 19th Century showed that heavy lead 45-70 bullets arriving at the end of their rainbow trajectories were extremely lethal.

 

[H2oPumper]

I look for 800 ft. lbs. on the charts to determine what the effective kill range could be, however, with any high caliber rifles that I have, it's out of my range. What I've gathered, my 7mm-08 is 600 yards, the 30-06 & 270 are 700 yards, and the 280 is 800 yards, based on the grain bullets I shoot; all my approximates. All those ranges are ethically out of my range.

 

[Lloyd Smale]

ft lbs of energy dont kill animals bullets do.

 

[Gunnerboy]

^ thats not always true, my father shot an elk with his 3006 at about 450-475 yds and swore that he hit it in the heart lung area we tracked that thing for over an hour found it dispatched it and when we gutted the elk his bullet was stuck in the heart about 3/4 the way thru, so its energy + the type of bullet that matters.

 

[Loosedhorse]

If it matters...

NE has regulations that cover minimum energy; they specifiy:

• Rifles* .22-caliber or larger that deliver at least 900 foot-pounds of energy at 100 yards
• Handguns* or muzzleloading handguns that deliverat least 400 foot-pounds of energy at 50 yards

Maryland specifies muzzle energy instead, but the requirements may not be practically much different than NE's:

Any modern handgun used for deer and bear hunting must have a barrel length of 6 inches or more and use ammunition which produces a muzzle energy of 700 foot-pounds or more...

•Rifles used for deer and bear hunting must use ammunition developing a muzzle energy of at least 1,200 foot pounds.

IL:

•For handguns...a factory load with the published ballistic tables of the manufacturer showing a capability of at least 500 foot pounds of energy at the muzzle.

SD:

Deer and antelope, for example, require a firearm that delivers at least 1,000 foot-pounds of energy from the muzzle...

CO:

...a rated impact energy one hundred (100) yards from the muzzle of at least one thousand (1000) foot pounds as determined by the manufacturer's rating...

 

[Jason_W]

FT-lbs of energy is not what kills game. Destroyed vital tissue kills game. There are multiple approaches to messing up a lot of vital tissue, all of which are valid.

 

[Gordon]

Wise regulations in NE IMHO. I use a .224 Weatherby with 60 grain Nosler Partition bullets at 3400 FPS which blow a golf ball sized exit hole thru a Blacktail, which is smaller than a whitetail. I'd prolly use a larger caliber if I go whitetailing again and for Mule deer for sure.

 

[finnwolf64]

ft-lbs energy should not be used alone in determining a rounds effectiveness. I've often seen where people post that a .22 magnum & a .44 special have similar ft-lbs energy and assume that they drop game similarly, which is not the case.

 

[JohnKSa]

ft lbs of energy dont kill animals bullets do.

Bullets only kill animals if they have ft lbs of energy. Bullets that don't move don't kill anything and if they move then they have ft lbs of energy.

The problem with kinetic energy as a primary criterion is that a gun is not a directed kinetic energy weapon...it's a directed PROJECTILE weapon.

It's meaningless to try to make a distinction between a directed kinetic energy weapon and a directed projectile weapon because kinetic energy and projectiles are essentially two sides of the same coin. A projectile, by definition has velocity and mass and that means it has kinetic energy. Anything that has kinetic energy must have mass and must be moving and therefore, by definition, is a projectile.

Kinetic energy is simply a measure of the projectile's potential to do work. There are many reasons why a projectile might not live up to it's energy "potential", however that doesn't change the meaning or validity of kinetic energy.

For what it's worth, I don't believe kinetic energy tells the whole story (or even comes close to telling the whole story) when it comes to terminal performance, but it is one part of many that makes up the puzzle that is terminal performance.

I also don't believe that arbitrary KE thresholds are particularly worthwhile. I had a friend who hunted deer with a .308 bolt rifle and a .357Mag levergun and said that his quickest kills were with the .357Mag, not the .308.

Clearly there's a little more to this puzzle than JUST energy, but that doesn't mean we should ignore it or try to explain it away.

SO, a 55 gr .243 is SCREAMING fast, and has HUGE initial KE, BUT it has very low mass - that's why it accelerates quickly

It accelerates in the time it takes it to get out of the barrel of the gun and that's a function of the pressure vs time curve of the cartridge discharge, bullet/barrel friction, barrel length as well as bullet mass. You are correct that all else being equal, a lighter bullet will accelerate faster and will probably attain a higher kinetic energy level.

...but also why it will DECELERATE quickly in tissue- and it loses kinetic energy EXPONENTIALLY as is slows.

How much a bullet resists being stopped is more a function of momentum than it is kinetic energy and momentum tends to favor heavier projectiles. So yes, all else being equal, a lighter bullet will tend to penetrate less and will decelerate faster. That's not so much a consequence of it's having higher energy as much as it is that it's not as efficient a penetrator due to it's having less momentum.

As far as the bullet "losing" kinetic energy, that is certainly true. However, while the bullet "loses" the kinetic energy, the kinetic energy is not "lost" to the entire system. It is, in fact, the loss (more accurately the rate of change of loss) of that kinetic energy by the bullet that determines, in large amount, the size of the temporary stretch cavity which, in rifle bullets, can do significant tissue damage.

Again, that's not all that matters, you still need sufficient penetration as even a very large but very shallow temporary stretch cavity won't do the job effectively. Basically you need kinetic energy, but you really need that kinetic energy balanced with enough momentum and with proper projectile design in order for things to work the way they should.

 

[jmr40]

FT-lbs of energy is not what kills game. Destroyed vital tissue kills game.

While this is true, energy numbers are a fairly accurate way to predict how much vital tisssue is destroyed.

An insufficiently robust bullet arriving at peak terminal velocity/energy from a 270 will surface shatter, leaving a nasty wound but a running deer. Whereas the Sandyhook trials at the end of the 19th Century showed that heavy lead 45-70 bullets arriving at the end of their rainbow trajectories were extremely lethal.

You are relying on 19th century science to solve 21st century problems. Bullets have come a long way since the 1800's. Modern 270 bullets will hold together quite well.

.243 is SCREAMING fast, and has HUGE initial KE, BUT it has very low mass - that's why it accelerates quickly, but also why it will DECELERATE quickly in tissue- and it loses kinetic energy EXPONENTIALLY as is slows.

Slow, heavy bullets may not look 'sexy' on paper, but they take large game consistantly and well. I'd rather have a .30-30 than a .243 for hogs, any day.

Same problem. This is not the 1800's anymore, or even the 1970's. While the 30-30 works as well as ever modern 243 bullets pushed at well over 3000 fps will hold together and punch completely through your hog leaving more damage than the 30-30.

 

[Jason_W]

While this is true, energy numbers are a fairly accurate way to predict how much vital tisssue is destroyed.

Only when comparing projectiles of similar diameter, mass, and construction.

For example, a 150 grain FMJ bullet fired from .308 win FMJ round will pack more KE than a 240 grain soft point fired from a .44 mag. In spite of it's significantly lower energy figures, the large diameter, heavy, and soft .44 bullet will destroy more tissue (assuming the shot is taken within 75 yards or so of the target, of course).

Energy figures may be useful for such apples to apples comparisons as a soft point .30-30 round to a .30-06 soft point round.

 

[RPRNY]

Bullets have come a long way since the 1800's. Modern 270 bullets will hold together quite well.

If they are indeed the correct bullets and well built, true. However, I have strong reservations, backed up by numerous field examples, about the Hornady SST/FTX at very high velocities effectively shattering. Jacketed bullets pushed too hard that shed their jacket are another issue. I was not suggesting that the answer is to use 19th Century bulllets, merely pointing out that velocity and/or kinetic energy alone don't complete the equation. Bullet mass and construction are a third pillar of the equation.