I just found this and thought it was interesting enough to share.

Rather than ft/lbs as an energy measure try this calculation. A Hunter named Taylor apparantly came up with it.

caliber of bullet times weight in grains times velocity in ft/sec. devided by 7000

.458 x 350 x 2500 / 7000= 57.25 458 win mag

.338x 200 x 2670 / 7000 = 25.78 338-06

.429 x 240 x 1350 / 7000= 19.85 44 magnum

.257 x 100 x 3250 / 7000 = 11.97 25-06

This was his calculation. I think it is more representative of what happens in real life.

There are arguments pro and con to Taylors formula. I think it works well for large game but falls short on small game. Regardless enough people thought it was useful to request it be added to PointBlank, which it was. Taylor tables are located in the Misc Functions part of PointBlank Software.


-DallanC

I am a bit uncertain about how to apply Taylor's formula versus foot/pounds of energy. All the best...
Gil

These numbers are still confusing to me. It's like In Jim Carmichael's "Book of the Rifle" wherein he talks about "momentum" and calculates it for various loads. It is good stuff for technicians to argue about, but for me, I like the old fashioned ft/lbs. It is something I can relate to and understand. And besides, as far as that buck is concerned, he can't calculate anyway Just put it where it should go and make it go as fast as you can. It'll get the job done.

All the best..............Blaine

Well I like Taylor's system , ftlbs favors light bullet weight and velocity , is not a true indicator of anything .. Just BIG numbers to impress you .. Besides if we used the ftlbs progressively as it werks for deer and moose etc , by the time you get to Cape Buffs and Elephant , you'd need a piece of field artillery ..
Jack

Taylors numbers are SPECIFICALLY to be used on dangerous game in Africa. He (Taylor) came up with this formula based on SOLIDS used on elephants, rhinos, etc. The number is the relative ability of the round to literally KO the animal & give the shooter a chance to administer a fatal blow IF the first shot missed (but was close).

IOW, for med size game and/or expanding bullets it's worthless.

Don't believe me? Buy the man's book.

Good points grimel , my book says the same thing..
Jack

Energy can be a very misleading term. As an example lets use a very commonrifle round vs a very common handgun round.

.308 Winchester 150gr PSP at 2750fps. SD = .225 ME = 2519ftlb

.44 Magnum 300gr WFN at 1175fps. SD = .232 ME = 919ftlb

Now lets set up the shot:

Heavy wooded area and you are on the ground due to it being mostly pines and a tree stand would limit your view. You have been going after a good buck in the area and have spotted him prior. You would estimate him at @ 280 lbs with total of 8 points. The rut is near and the deer have really packed on the weight and the temp is around the low to mid 20s so the coat is full also.

You spot your buck at 35 yards, you have a clear shot at him quartering away and your shot will hit him behind the diaphram and have to quarter thru him to hit any vitals.
If you don't take the shot in a few seconds he will be out of sight and you don't know if you will get another chance.

I will tell you this, both will kill the deer. I would venture to say that the .308 will make a mess and more than likely will not exit the deer. The deer will travel 50 yards plus and not leave much of a trail. When you do find him the lung will be demolished and the heart will have some damage also if you did your part you will probably find the remains of your bullet here. The tracking will be very difficult and you need to look very hard for your deer.

If you are using the .44 Mag, it will punch through the deer and do some major damage to the lung, it will pass through the heart/or aortic area tearing up vessels/arteries and will exit the chest never to be found. Your deer will possibly travel a couple steps to maybe 50 yards maximum and will leave a blood trail that will look like the Yellow Brick Road.

The reason that I stated this is that bullets do funny things, SD to me is a better measure of a bullets possible performance along with its construction and makeup. That same 150gr bullet if it was a Nosler Partition would do ablut the same as the .44 bullet by exiting as would a Barnes XBT and some other Premium Bullets. One thing about the .44 is that it hits the target at a diameter that the rifle bullet has to expand to, The WFNs entry hole will be @ .400 diameter and look like a cookie cutter went in and the path of damage will be @ 3 - 4" in diameter all the way through the lung with an exit @1".

This is why I don't rely on energy formulas, the above situation happened to me so I can tell you both deer were recovered, the one hit with the .308 went just under 75 yards and piled up behind a fallen tree, the one hit with the .44 went 2 steps and fell over dead.

Pay attention to the construction of your bullet and the placement of your shot, also the larger the animal, heavier the hide & bones go to a higher SD on your bullet, look at the performance of the 6.5 X 55 Mauser. The 140gr will normally out penetrate any 150 - 165gr .308 bullet out there.