A SIMPLE KILLING POWER FORMULA

Bogie35 · Post by **Bogie35** » Tue Dec 23, 2008 1:28 am

Hey fellas. I'm kind of a geek when it comes to crunching numbers. I just love it. I have spent an embarrassing number of hours over the last couple years experimenting with various formulas regarding "killing power". The idea is to have a quick and simple way to determine a cartridge's potential killing power. Of course, the most important factors to consider are BULLET CONSTRUCTION and SHOT PLACEMENT, however with these being relatively equal, how do different cartridges compare?

First of all, the formulas that simply don't add up:

ENERGY - It only takes into account a bullet's WEIGHT and VELOCITY, and we all know there's more to it than that. It also indicates that VELOCITY is twice as important as WEIGHT. I wonder how the "big, slow-moving bullet" fans feel about that?

TAYLOR'S KNOCKOUT VALUE - It takes into account the bullet's WEIGHT, VELOCITY, and DIAMETER. However, it doesn't effectively represent PENETRATION, most frequently indicated by the bullet's SECTIONAL DENSITY.
G&S ONLINE'S KILLING POWER - It would be pretty accurate if it used MOMENTUM instead of ENERGY; and simpler if it used DIAMETER instead of FRONTAL AREA.
MATUNAS' OPTIMAL GAME WEIGHT FORMULA - This formula is far too complicated. And since when is a 105 grain 6mm Rem. more adequate for elk inside 100 yards than a 375 Winchester?

Now, my formula:

BOGIE'S TERMINAL POTENTIAL

TP = DIAMETER x WEIGHT x SECTIONAL DENSITY x VELOCITY x .001342

It takes into account the major factors of a bullet's terminal performance; It's WEIGHT, VELOCITY, DIAMETER, and SECTIONAL DENSITY. Each factor is easily found in most cartridges' ballistic information, and each factor is given equal importance. WEIGHT and VELOCITY combine to mathematically represent the bullet's MOMENTUM. The DIAMETER relatively represents the potential CIRCUMFERENCE of the WOUND CHANNEL. And the SECTIONAL DENSITY relatively represents the potential DEPTH of the WOUND CHANNEL, or PENETRATION. The most accurate representation of killing power is the VOLUME of the WOUND CHANNEL that develops when a bullet passes through an animal. Generally speaking, the wider and deeper the wound, the surer and quicker the kill.

Plug in your own numbers, and tell me what you think!

Thanks,
bogie

Bogie35 · Post by **Bogie35** » Tue Dec 23, 2008 1:42 am

Here's some examples:

At 100 yards, a typical 180gr 30-06 impacting at 2480fps will have a TP of "50.00".
A 170gr 30-30 at 1870fps, TP = 33.63
A 200gr 35 Rem at 1695fps, TP = 36.30
A 300gr 45-70 at 1500fps, TP = 56.49
A 150 270 Win at 2580fps, TP = 40.16
A 240gr 44 Mag at 1380fps, TP = 35.51

bogie

Tycer · Post by **Tycer** » Tue Dec 23, 2008 6:57 am

141.45
68.14
52.79
42.74
39.60

Works for me!

Idiot · Post by **Idiot** » Tue Dec 23, 2008 9:21 am

Stalk close and punch a .348" wide Barnes 220 grain X-Bullet going 2,000 fps through the shoulder - on through the heart - and out the other side equals deader-than-Lincoln (m71/.348@220X2,000.s.p.ext=300lbsdw). Seems like a pretty simple formula to me.

Bogie35 · Post by **Bogie35** » Tue Dec 23, 2008 11:41 am

Idiot wrote:Stalk close and punch a .348" wide Barnes 220 grain X-Bullet going 2,000 fps through the shoulder - on through the heart - and out the other side equals deader-than-Lincoln (m71/.348@220X2,000.s.p.ext=300lbsdw). Seems like a pretty simple formula to me.

The TP = 53.33, which is of course......deader-than-Lincoln......and 300lbs.dw!

bogie

Buck Elliott · Post by **Buck Elliott** » Tue Dec 23, 2008 12:02 pm

SHOT PLACEMENT --- PERIOD (almost..)

I find Taylor's formula works well enough for the other factors. Sectional density IS a function of weight & diameter, which also completely ignores bullet nose-shape.

Don't forget, Taylor was talking about shooting elephants and other gigantic beasties at close to muzzle ranges.

You may have stumbled onto something useful in your calculations, and then again, maybe not...

Just hit 'em where they live and you'll do all right. I won't tell you how many deer I've put down with a .22 LR.

JohndeFresno · Post by **JohndeFresno** » Tue Dec 23, 2008 1:16 pm

That looks appealing to me. Before I start plugging in the formula to the loads I have on a database, I am wondering if there is a way to further refine this formula by adding the meplat into the mix.

I am thinking that a .45 Wide Flatnose (WFN) would hit harder than an old style roundnose, for instance; and that a .30-30 flatnose would have more shock power at the same speed than a pointed projectile (leaving out differences in expansion from the bullet construction, of course).

mod71alaska · Post by **mod71alaska** » Tue Dec 23, 2008 1:55 pm

I have a much simpler formula....

Hunting skills + a favorite rifle of sufficient caliber and quality bullet for the game you're hunting + shot placement = a successful trophy or meat hunt with minimal waste. Been keeping it simple and having success for a long time.

Bogie35 · Post by **Bogie35** » Tue Dec 23, 2008 3:44 pm

JohndeFresno wrote:That looks appealing to me. Before I start plugging in the formula to the loads I have on a database, I am wondering if there is a way to further refine this formula by adding the meplat into the mix.

I am thinking that a .45 Wide Flatnose (WFN) would hit harder than an old style roundnose, for instance; and that a .30-30 flatnose would have more shock power at the same speed than a pointed projectile (leaving out differences in expansion from the bullet construction, of course).

The formula is best for comparing cartridges with similar bullet construction and nose profile. You could add a few points for a flat nose and for a larger meplat, but then it would get more complicated. The idea is a quick and simple formula.

A flat nose with a large meplat will "hit harder", however the nose will deform as it penetrates. The best proven thing about a larger meplat is that it helps initiate bullet expansion. But, some say that a large meplat on a hard cast bullet will create a more "permanent" wound channel that won't close and possibly seal itself after the bullet passes through. That's a whole new topic though!

If a large meplat was the magic factor in killing power, then we would see a lot more wadcutter hunting loads on the shelves. Besides, it's not how hard a bullet slaps the animal that matters, it's what the bullet does afterward.

Here's a thought provoking link:

http://www.buffalobore.com/ammunition/meplats.htm

Thanks for your input,
bogie

pharmseller · Post by **pharmseller** » Tue Dec 23, 2008 4:25 pm

mod71alaska wrote:I have a much simpler formula....

Hunting skills + a favorite rifle of sufficient caliber and quality bullet for the game you're hunting + shot placement = a successful trophy or meat hunt with minimal waste. Been keeping it simple and having success for a long time.

+1 as long as it's a model 71...

P

1886 · Post by **1886** » Tue Dec 23, 2008 5:07 pm

Seems well thought out. I think I like it. 1886.

AJMD429 · Post by **AJMD429** » Tue Dec 23, 2008 6:06 pm

If sectional density is a function of weight and diameter, then theoretically you could leave it out and adjust the formula to compute s.d. in the process by using the weight and diameter. This would help if you don't have a table to look up the s.d., and if you don't have such a table, you'll have to do the math one way or another anyway...

Still, I like it.

Bullard4075 · Post by **Bullard4075** » Tue Dec 23, 2008 7:43 pm

"I won't tell you how many deer I've put down with a .22 LR."

What would cause one to shoot a Deer with a 22LR ?

By "put down" I'm assuming you are talking about finishing off road-kill or some such.

JohndeFresno · Post by **JohndeFresno** » Tue Dec 23, 2008 9:02 pm

Ok, I plugged these into my database. Here are some examples of various loads for different firearms. You can compare the ME, Taylor (computed) Index number, and the Bogie TP Index and see for yourself.

Don't worry about the specific bullet descriptions; I just used an existing report and plugged some stuff in. There was no attempt to modify the Bogie TP using the bullet composition or type.

HandLoad - BogieTP Test – LeverGuns.Com

223 Remington (.224) - 55 gr., 3034 fps / ME 1124.47 ft. lbs. / TKO: 5.3 / BOGIE: 7.88
270 Winchester (.277) - 150 gr., 2800 fps / ME 2611.94 ft. lbs. / TKO: 16.6 / BOGIE: 43.56
30-06 (.308) - 100 gr., 2011 fps / ME 898.21 ft. lbs. / TKO: 8.8 / BOGIE: 12.55
30-06 (.308) - 180 gr., 2818 fps / ME 3174.76 ft. lbs. / TKO: 22.3 / BOGIE: 56.82
30-06 (.308) - 200 gr., 2672 fps / ME 3171.46 ft. lbs. / TKO: 23.5 / BOGIE: 66.49
30-06 M1 Garand (.308) - 168 gr., 2600 fps / ME 2522.39 ft. lbs. / TKO: 19.2 / BOGIE: 45.68
30-30 Winchester (.308) - 150 gr., 2136 fps / ME 1520.02 ft. lbs. / TKO: 14.1 / BOGIE: 29.93
30-30 Winchester (.308) - 170 gr., 2108 fps / ME 1677.82 ft. lbs. / TKO: 15.8 / BOGIE: 37.92
32 ACP (.312) - 60 gr., 825 fps / ME 90.70 ft. lbs. / TKO: 2.2 / BOGIE: 1.82
357 Magnum (.357) - 158 gr., 1200 fps / ME 505.33 ft. lbs. / TKO: 9.7 / BOGIE: 16.08
38 Special (.357) - 125 gr., 980 fps / ME 266.64 ft. lbs. / TKO: 6.2 / BOGIE: 8.22
38 Special (.358) - 158 gr., 800 fps / ME 224.59 ft. lbs. / TKO: 6.5 / BOGIE: 10.69
40 S&W (.400) - 155 gr., 1000 fps / ME 344.26 ft. lbs. / TKO: 8.9 / BOGIE: 11.48
40 S&W (.400) - 165 gr., 1022 fps / ME 382.77 ft. lbs. / TKO: 9.6 / BOGIE: 13.31
40 S&W (.400) - 155 gr., 909 fps / ME 284.46 ft. lbs. / TKO: 8.1 / BOGIE: 10.44
44 Magnum (.430) - 240 gr., 1078 fps / ME 619.45 ft. lbs. / TKO: 15.9 / BOGIE: 27.62
44 Magnum (.430) - 200 gr., 1500 fps / ME 999.47 ft. lbs. / TKO: 18.4 / BOGIE: 26.83
44 Magnum (.430) - 310 gr., 1275 fps / ME 1119.28 ft. lbs. / TKO: 24.3 / BOGIE: 54.74
44 Magnum (.430) - 240 gr., 1652 fps / ME 1454.75 ft. lbs. / TKO: 24.4 / BOGIE: 42.33
44 Special (.430) - 180 gr., 850 fps / ME 288.85 ft. lbs. / TKO: 9.4 / BOGIE: 12.27
44 Special 2 in (.430) - 200 gr., 869 fps / ME 335.45 ft. lbs. / TKO: 10.7 / BOGIE: 15.95
45 Auto (.451) - 185 gr., 898 fps / ME 331.34 ft. lbs. / TKO: 10.7 / BOGIE: 13.07
45-70 1895 Marlin (.458) - 350 gr., 1850 fps / ME 2660.53 ft. lbs. / TKO: 42.4 / BOGIE: 94.72
45-70 1895 Marlin (.458) - 405 gr., 1550 fps / ME 2161.10 ft. lbs. / TKO: 41.1 / BOGIE: 121.15
45-70 1895 Marlin (.459) - 430 gr., 1700 fps / ME 2760.08 ft. lbs. / TKO: 47.9 / BOGIE: 131.48
45-70 Govt Trapdoor (.458) - 405 gr., 1650 fps / ME 2448.94 ft. lbs. / TKO: 43.7 / BOGIE: 113.36
7.62x39 Russian (.310) - 123 gr., 2400 fps / ME 1573.56 ft. lbs. / TKO: 13.1 / BOGIE: 33.77
7.62x39 Russian (.310) - 173 gr., 1704 fps / ME 1115.68 ft. lbs. / TKO: 13.1 / BOGIE: 31.89
8mm Mauser (.323) - 195 gr., 2300 fps / ME 2291.11 ft. lbs. / TKO: 20.7 / BOGIE: 51.91
8mm Mauser (.323) - 195 gr., 2491 fps / ME 2687.44 ft. lbs. / TKO: 22.4 / BOGIE: 56.22
8mm Mauser (.323) - 150 gr., 2700 fps / ME 2428.70 ft. lbs. / TKO: 18.7 / BOGIE: 35.99
9mm Luger (.355) - 124 gr., 1100 fps / ME 333.24 ft. lbs. / TKO: 6.9 / BOGIE: 9.16

KirkD · Post by **KirkD** » Tue Dec 23, 2008 11:34 pm

Shouldn't it be .001429 instead of .001342? (assuming your bullet weight is in grains)

What about expansion? That will change the diameter and the sectional density. Also, sectional density, for bullets that are primarily lead, is closely related to weight and diameter. Since we already have those things in the equation, I think we can drop sectional density.

Bogie35 · Post by **Bogie35** » Wed Dec 24, 2008 12:16 am

KirkD wrote:Shouldn't it be .001429 instead of .001342? (assuming your bullet weight is in grains)

What about expansion? That will change the diameter and the sectional density. Also, sectional density, for bullets that are primarily lead, is closely related to weight and diameter. Since we already have those things in the equation, I think we can drop sectional density.

Hey Kirk. The .001342 has no mathematical significance. It's just an arbitrary standard to bring the final value into a more familiar range, i.e. 1-100 or so. Honestly, since the 30-06 is so common and well known, I used .001342 simply because it gave a typical factory 180gr 30-06 load a nice round value of 50.00 at 100 yards.

1/7000 is actually .0001429. Although it makes good mathematical sense, I simply liked having larger final values to compare. It was just easier to wrap my mind around!

Thanks for your input.

bogie

JohndeFresno · Post by **JohndeFresno** » Wed Dec 24, 2008 12:20 am

I removed the SD from the formula and two things happened:
1) Numbers too high and cumbersome, as referenced above
2) Not enough variance between the numbers to show difference in power curve - see below (I just pasted it from a quick spreadsheet; hope it formats correctly). The first number is the Bogie number; the second number is the same formula without the SD. The first cartridge is a .223 Remington, and so on. The first number can be differentiated from the second because it has only one decimal.

4.4 42.8769
13.3 90.520584
12.7 86.3577
23.4 137.555
22.4 160.99974
26.8 173.118
27.6 178.8886
35.4 191.122272
36.0 193.89216
24.4 131.56968
30.7 158.6915

Bogie35 · Post by **Bogie35** » Wed Dec 24, 2008 12:25 am

Remember, the primary goal was to develop a very simple, but reasonably accurate formula to use in comparing various cartridges.

All in all, considering the formula's simplicity, it generates surprisingly valid results for comparison purposes.

Thanks to all for the input, and please keep it coming!

bogie

Bogie35 · Post by **Bogie35** » Wed Dec 24, 2008 12:48 am

JohndeFresno wrote:I removed the SD from the formula and two things happened:
1) Numbers too high and cumbersome, as referenced above
2) Not enough variance between the numbers to show difference in power curve - see below (I just pasted it from a quick spreadsheet; hope it formats correctly). The first number is the Bogie number; the second number is the same formula without the SD. The first cartridge is a .223 Remington, and so on. The first number can be differentiated from the second because it has only one decimal.

4.4 42.8769
13.3 90.520584
12.7 86.3577
23.4 137.555
22.4 160.99974
26.8 173.118
27.6 178.8886
35.4 191.122272
36.0 193.89216
24.4 131.56968
30.7 158.6915

Hey John. Initially, I tried to eliminate using Sectional Density, but the final values didn't seem to jive with "real world" hunting experience. For instance, without using SD a 200gr 35 Rem would have a higher 100 yard value than a 150gr 270 Win......or a 200gr 35 Rem would have about the same value at the muzzle as a 180gr 30-06. These results just didn't make good sense to me.

When I used SD, everything seemed to fall into place with "real world" experience. Apparently, penetration matters a little more than the circumference of the hole. In fact, it's probably safe to say that PENETRATION IS WHAT KILLS, WHILE THE SIZE OF THE HOLE INDICATES HOW QUICKLY IT WILL HAPPEN.

Thanks. You're a man after my own heart!

bogie

JohndeFresno · Post by **JohndeFresno** » Wed Dec 24, 2008 12:54 am

Good job, Bogie. I like it as you configured it. I've made it a permanent part of my "Handload" database as a heads up display when I enter my loads. As stated, accuracy counts; but this is another tool in our collective belt, and appears to be more meaningful than "Muzzle Energy." Thanks.

PaulB · Post by **PaulB** » Wed Dec 24, 2008 2:41 am

Uh, I don't think so.

Your formula is 2R x W x W/("pi"xRxR) x V, where R is bullet radius and V is velocity. Simplifying, that is 2 (WxWxV)/("pi"xR), which gives too much importance to bullet weight, and is INVERSELY proportional to bullet diameter.

I don't have much use for these various formulas, although I think TKO may be a little better for non-expanding bullets. But none of them are good for comparing heavy, slow, non-expanding bullets with high velocity, expanding bullets.

Buck Elliott · Post by **Buck Elliott** » Wed Dec 24, 2008 11:52 am

Bullard4075 wrote:"I won't tell you how many deer I've put down with a .22 LR."

What would cause one to shoot a Deer with a 22LR ?

By "put down" I'm assuming you are talking about finishing off road-kill or some such.

Nope; I mean killed -- shot -- collected for camp meat -- culled... and yeah, I've "put down" a few wounded ones with the lowly .22. I prefer something larger, of course, usually something that starts with a 4 and ends with a 5, but you use what you have at hand.

You get as close as you can, then get closer, and put the bullet right where it will do the most good, or else you don't shoot.

Bogie35 · Post by **Bogie35** » Wed Dec 24, 2008 2:27 pm

It's not about which cartridge can or can't kill. It's just a very simple guide to responsible cartridge selection. In other words, it's a lot better than, "Hey y'all watch this! I'm gonna see if I can kill that deer with this 22LR".

22LR - 1.72
30/30 - 32.90
35 Rem. - 43.90

The above shows that the 30-30 and the 35 Rem. are much better choices for hunting deer than the 22LR, even if you "sneak real close".

bogie

PaulB · Post by **PaulB** » Wed Dec 24, 2008 3:53 pm

If you have two .44 caliber 300 grain bullets, and swage one of them down to .22 caliber, and then launch them both at 1000fps at deer, your formula will predict the .22 has twice the killing power of the .44.

Sectional density is great - until it is high enough to give complete penetration (some - not me - might say all you need is enough to get into the vitals). Above that point, increased sectional density is utterly worthless. Although some might use the extra to allow them to take "texas heart shots".

You might find some point where the .22 actually has more killing power than the .44, for example, very light bullets into very heavy game. But you can see why I've given up on all such formulae.

You don't need them. You just need some common sense. Don't use .22LR for shooting brown bear. Don't use a .38SPL round nose lead for taking on cape buffalo. And so forth. Any caliber, used with some common sense, is good enough if your shot placement is reasonable and the bullet construction is proper. No caliber is 100% perfect.

JohndeFresno · Post by **JohndeFresno** » Wed Dec 24, 2008 4:49 pm

I think that there are a lot of people beating this to death. It's a simple tool that helps, among other things, to allow you to sort out, albeit roughly, data, such as on a database (what I will be using it for). In my military experience, then my 38 years plus as a peace officer, starting with 20 years of experience in all aspects of being a deputy sheriff, I have seen pet firearm statistics and knockdown theories come and go. The FBI bought into this "hydrostatic shock" nonsense in the sixties, aping what some misguided engineers said about hydrostatic shock being the one factor that incapacitates; then later switched to the larger .40 caliber and found that their female agents (primarily, let's not get hung up on political correctness) could not handle it, so the .40 SW was developed as a "10mm light" load and it caught on. Of course, many or most police agencies swallowed whatever the FBI said, as if it were the Gospel.

And when things got dicey and there were some particularly nasty shootouts, their trainers and SWAT guys wisely realized that a larger caliber, like the good ol' .45 with its outdated slow-moving large caliber, was still the best when you REALLY need to drop a very dangerous person very quickly. "Mortal wounds," they had realized too late - and a few dead agents later, did not amount to anything when it comes to saving lives during an active attack and shootout.

The Army and other Armed Forces followed the same stupid line of reasoning with their pure statistics approach and gave us the .22 caliber to fight a bush war (frequently) in Viet Nam. Again, part of their reasoning was that the smaller statured Vietnamese allies were more comfortable with a light-kicking gun - let's face the facts. Yes, that is documented, among other reasons.

But when the real crazies of the extremist Muslim factions didn't care if they lived or died, the Special Ops guys realized that the tried and true .308, .45 ACP, and other large, truly hard hitting calibers were the medicine to use, which they demanded.

I, for one, don't take ANY engineer too seriously, given the many misguided theories that were forced upon me as a law enforcement officer throughout my career. That is, for a while I was forced to carry a ridiculously ineffective subsonic 9mm when I had an excellent Mk IV Series 70 .45 that concealed better and hit harder.

But I respect an engineer's or statistician's training and recognize that he may have some input that is PART of the picture. I personally carry a .45 ACP with 235 grain hollowpoints by Federal - fast, hard hitting and explosive - as my concealed weapon, most of the time. I KNOW that it works; but if I am stuck with using a puny caliber like the .38 or 9mm (my opinion, of course - this should rankle some of you!), then I want to know every single thing about it that I can.

The same with hunting rounds. I agree with most here that the .30-30 is one of the greatest all around hunting rounds for the Continental US, and that the .45-70 will handle any big American game at reasonable distances; but it's nice to work up stats, anyway. Anyway, from what I have seen so far, this theory looks about as sound as the Taylor Knockout Index; and possibly more. More experimentation and analysis will tell.

Bogie35 · Post by **Bogie35** » Wed Dec 24, 2008 11:26 pm

PaulB wrote:If you have two .44 caliber 300 grain bullets, and swage one of them down to .22 caliber, and then launch them both at 1000fps at deer, your formula will predict the .22 has twice the killing power of the .44.

You're right. The formula will produce invalid results when making RIDICULOUS comparisons. A "300 grain 22 bullet" would look more like a metal stick than a bullet, so you would probably have to use a bow instead of a gun to launch it.

BTW, if you did find a way to launch it, a 300 grain 22 will likely penetrate nearly 6 times deeper than a 300 grain 44. That sounds pretty powerful to me.

bogie

JohndeFresno · Post by **JohndeFresno** » Sun Oct 25, 2009 2:42 am

UPDATE
As seen in the above postings, Bogie35 came up with an interesting variation on the TKO formula. As has been expounded, the true test is in the field with real game; but this is at least an interesting exercise in mathematics in an effort to determine the power range of a load.

Some time has passed since this post was last visited. In the interim, I have put together 176 loads (from my database) of various handgun and rifle loads, from .22 Long Rifle through .45-70 Government, with calculated Taylor Knockout Out (TKO) figures and Bogie35's formula; what I call Bogie TP.

The listings include some factory loads; I merely plugged in the calibers, known or claimed velocities and bullet weights with the formulae shown below to generate the results.

To refresh your memory:

TKO =[Bullet Wt]*[Velocity]*[Bullet Caliber]/7000
Bogie TP =[Bullet Caliber]*[Bullet Wt]*[SD]*[Velocity]*0.001342

Where -
Bullet Wt = grains, e.g. 158 gr.;
Velocity = Muzzle Velocity expressed in ft. per sec.;
Bullet Caliber = inches, e.g. .308 caliber;
SD = Sectional Densite expressed as a decimal

Here's the TKO table:

Two PDF files (visible on any system) were prepared from the spreadsheets that show these figures, in a .ZIP file that you can download with this link:
http://www.box.net/shared/4femvtikeg

The "TerminalTKO_CaliberSort.zip" download holds two PDF files:
1) TerminalTKO_CaliberSort.pdf -
a listing as shown below, sorted by Cartridge name (This is a small section, showing the some .30-06 and 30-30 loads)

2) TerminalTKO_DifferenceSort.pdf -
the same listing as #1, but sorted by the TKO/Bogie TP differential; the product of dividing the TKO figure into the Bogie TP number. With this sorted list, you can see the many instances where the ratio between the two formulae is surprisingly the same!

rhead · Post by **rhead** » Sun Oct 25, 2009 4:38 am

KP=1/PR

KP= killing power

PR= pulse rate of the target

Bogie35 · Post by **Bogie35** » Sun Oct 25, 2009 8:13 am

Thanks for the info John.

The Taylor TKO is an excellent method, however it doesn't penalize or reward enough for Sectional Density (SD), which is a vital factor in penetration potential. It has been my experience that, in general, penetration is the most fundamental factor in killing power. And SD and Bullet Weight are of equal importance in calculating penetration potential. Therefore, for large differences in SD, my formula will reward the greater SD more so than the TKO formula will. I like to think of my formula as a somewhat more technically accurate and specific form of the TKO formula, and only slightly more complicated.

Try this. Pick 3 different calibers that you have significant hunting experience with. Plug in the numbers and see if they correlate with your real world experiences. I would like to know what you find so I can make further adjustments if necessary.

Thanks,
bogie

86er · Post by **86er** » Sun Oct 25, 2009 9:21 am

I enjoy Bogie35's formula as a comparison tool. If it were to be all inclusive, I agree somewhat with KirkD that the sectional density is a factor that changes as the bullet penetrates (expansion, smearing, breaking) and changes the frontal diameter as it penetrates. A way to add those factors would be to know what the S.D. of the complete bullet is and what the maximum expansion is also. Those two factors can be combined with the overall wound channel at start and finish. Like John de Fresno said "...too complicated".

In my new book I have a simple formula to determine if a cartridge is adequate for a certain sized animal. Since the book deals with exotic animals exclusively, the weights vary greatly and some folks are not familiar with them. Also, the biological structure of exotics is different that that of North American native animals, or those that have been on N.A. for centuries. This formula takes into account the type of bullet, cup and core traditional jacketed bullet or premium bonded core jacketed bullet. You can figure a cast bullet too. What my formula will do is tell you if you have enough cartridge for the exotic game. For example: A 450 pound animal will tell you you need a 117.50 grain premium bonded bullet for minimal adequacy. Clearly this could be a 120 gr 25-06 or something similar. If you use the formula with a cup and core bullet it will tell you that a heavier bullet is required. It is not as complex as it sounds here. By contract and copyright I am prohibited from posting on a public forum the formula (sorry) but it is in my book.

Bogie35's excellent formula is a great compliment to my formula. They work well together. Here's how - I am going to hunt a Markhor Ram. The outfitter tells me they weight 300 pounds but are exceedingly tough and should be treated as such. I punch in the #'s into the JAR formula (mine). It tells me the bullet weight with Remington Core-Lokts needs to be X. I have two cartridges that have at least X. I punch in the #'s to Bogie35's formula to determine which of the two would give me a "power" advantage. A great set of tools to determine the proper caliber and bullet for the job!

Nice going Bogie35 and congratulations!

Bogie35 · Post by **Bogie35** » Sun Oct 25, 2009 9:28 am

86er wrote:I enjoy Bogie35's formula as a comparison tool. If it were to be all inclusive, I agree somewhat with KirkD that the sectional density is a factor that changes as the bullet penetrates (expansion, smearing, breaking) and changes the frontal diameter as it penetrates. A way to add those factors would be to know what the S.D. of the complete bullet is and what the maximum expansion is also. Those two factors can be combined with the overall wound channel at start and finish. Like John de Fresno said "...too complicated".

In my new book I have a simple formula to determine if a cartridge is adequate for a certain sized animal. Since the book deals with exotic animals exclusively, the weights vary greatly and some folks are not familiar with them. Also, the biological structure of exotics is different that that of North American native animals, or those that have been on N.A. for centuries. This formula takes into account the type of bullet, cup and core traditional jacketed bullet or premium bonded core jacketed bullet. You can figure a cast bullet too. What my formula will do is tell you if you have enough cartridge for the exotic game. For example: A 450 pound animal will tell you you need a 117.50 grain premium bonded bullet for minimal adequacy. Clearly this could be a 120 gr 25-06 or something similar. If you use the formula with a cup and core bullet it will tell you that a heavier bullet is required. It is not as complex as it sounds here. By contract and copyright I am prohibited from posting on a public forum the formula (sorry) but it is in my book.

Bogie35's excellent formula is a great compliment to my formula. They work well together. Here's how - I am going to hunt a Markhor Ram. The outfitter tells me they weight 300 pounds but are exceedingly tough and should be treated as such. I punch in the #'s into the JAR formula (mine). It tells me the bullet weight with Remington Core-Lokts needs to be X. I have two cartridges that have at least X. I punch in the #'s to Bogie35's formula to determine which of the two would give me a "power" advantage. A great set of tools to determine the proper caliber and bullet for the job!

Nice going Bogie35 and congratulations!

Thanks! That has enormous meaning coming from you, sir. I look forward to reading your new book when I get it.

bogie

Don McDowell · Post by **Don McDowell** » Sun Oct 25, 2009 9:44 am

Bogie35 wrote:

Try this. Pick 3 different calibers that you have significant hunting experience with. Plug in the numbers and see if they correlate with your real world experiences. I would like to know what you find so I can make further adjustments if necessary.

Thanks,
bogie

These charts and formula's always make for interesting reading. However they seldom if ever have much to do with real world results. There isn't a one of these formulas, that would let a person think that a 30-30, 243, or 250 savage etc are capable of anything bigger than a small deer. That just doesn't line up with having seen on many occasions the bangflop kills on animals such as elk and shiras moose with those cartridges , and done at ranges past which most "experts" think.
Ever seen dead deer caused by a 32-20? What do the charts say about that? Elk with a 25-20? Not my cup of tea but I know of it happening.

Bogie35 · Post by **Bogie35** » Sun Oct 25, 2009 10:39 am

Don McDowell wrote:
Bogie35 wrote:

Try this. Pick 3 different calibers that you have significant hunting experience with. Plug in the numbers and see if they correlate with your real world experiences. I would like to know what you find so I can make further adjustments if necessary.

Thanks,
bogie
These charts and formula's always make for interesting reading. However they seldom if ever have much to do with real world results. There isn't a one of these formulas, that would let a person think that a 30-30, 243, or 250 savage etc are capable of anything bigger than a small deer. That just doesn't line up with having seen on many occasions the bangflop kills on animals such as elk and shiras moose with those cartridges , and done at ranges past which most "experts" think.
Ever seen dead deer caused by a 32-20? What do the charts say about that? Elk with a 25-20? Not my cup of tea but I know of it happening.

Hey Don. You are absolutely right. But the problem is not the formula, rather it's the limits that gunwriters set for killing power. They keep raising the minimum. Using my formula, many of them would say that you need a "Bogie TP" of at least 35 to kill a deer cleanly. However, in the real world (with proper bullet placement), we know that a deer will die humanely from a Bogie TP of 18 or so (which is about what a 158 grain 357 Mag would read at 125 yards or so). So, it's not the formula that's at fault. It's the unrealistic "requirements" issued by gunwriters.

Thanks,
bogie

Modoc ED · Post by **Modoc ED** » Sun Oct 25, 2009 10:51 am

Bullard4075 wrote:"I won't tell you how many deer I've put down with a .22 LR."

What would cause one to shoot a Deer with a 22LR ?

POACHING!!!! Many poachers take deer with a .22LR at night while spotlighting them in the dark. Used to be especially popular with poachers in the Shennandoah National Forest on the VA, WV, border.

Don McDowell · Post by **Don McDowell** » Sun Oct 25, 2009 10:52 am

Bogie thats a true fact. I've always been amazed at the number of folks that whoop and holler you have to have 1000 fpe at point of impact to take a deer, yet those same folks turn around and sing the high praises of 44,41and 357 handguns, and none of those will make 1000 fpe at the muzzle.

You did a good job on your formula and are to be commended for your effort.

Lastmohecken · Post by **Lastmohecken** » Sun Oct 25, 2009 12:59 pm

That's maybe as good a formula as any other. Like all killing formulas, It still doesn't tell the whole story. And Bullet placement doesn't always tell the whole story either.

Of course a brain shot, or solid hit to the nervious system, will usually drop an animal in it's tracks. But any other hit, may or maynot regardless of where you hit it.

A prime example of this is, one time I hunting deer crossing an open field, sometimes running, sometimes not. AT this particular time, I was into a Remington Classic 700 in 375 HH Mag, so I of course I was testing it on deer, using a pretty hot load, behind a 235 gr Spear.

The first buck I shot, was running to beat the band, with those long stretched out, up and down jumps. The range was about a hundred yds. Ok, My shooting wasn't too good, but my third shot caught it right at the bottom of the belly, almost a miss. The deer rolled up like a sack of potatos, with the Classic dead right there flop as they say. On examination, it was techically a gut shot, but all it did was open up the bottom of the belly, I field dressed it, and found no ovious damage to any major organs or nervious system. Why did the deer die instantly?

My second deer was doe, range 80yds standing. I put one shot through the lungs, perfect placement. The deer took off, and ran, probably at least 125yds, and ended up dead at the bottom of a little gully. I have seen the same thing happen, more then once, using a .270 win with 130gr bullets.

Third deer was a heavy buck, shot at about 150yds or maybe farther. It was doing a steady ground eating walk and I didn't allow enough lead. I hit it right in front of the hind quarters, and missed the spine. It dropped like a rock and was totally dead, when I got to it. Go figure.

Another lighter buck was shot the following year, on the move, with both me and my son shooting at it, it was probably dead on it's feet after the first round, but gave little indication of a hit, we ended up shooting it 4 times before it went down. It probably went 75 yds after the first hit. 375 mag again and a .308 win using 180gr silvertips.

I have often seen the same bullet placement, drop one deer in it's tracks, and the next run a hundred yds.

Some hits, make perfect sense, and some are baffling, as to the reaction of the animal hit. I am not a big fan of much of anything under 30 caliber, although I have had outstanding luck with a 25-06 using 100 bullets, as opposed to the .270 using 130 gr bullets, but I have take a lot of deer with the .270. I think my favorite all around is the .308 with 180gr silvertips.

But the 350Rem Mag has always been outstanding for me, and I have had good luck with several other calibers such as the .444, 45-70, etc.

I say get a proven caliber, find a good bullet, and shoot straight. Some will fall dead right there, but some will most likely go a little ways before expiring. The heaiver the game, go with more caliber, and more bullet weight, as long as you can effectively shoot the bigger gun.

JohndeFresno · Post by **JohndeFresno** » Sun Oct 25, 2009 2:39 pm

Bogie35 wrote:...Try this. Pick 3 different calibers that you have significant hunting experience with. Plug in the numbers and see if they correlate with your real world experiences. I would like to know what you find so I can make further adjustments if necessary.

Thanks,
bogie

Bogie35,

I defer to 86er and other professionals. My hunting experience pales in comparison to theirs, but now that I'm retired (from a demanding job), I plan to even up the odds a little in the near future.

Grizz · Post by **Grizz** » Sun Oct 25, 2009 3:29 pm

it's interesting to see all the calculating and trying to visualize what it means.

I didn't see mention of momentum or meplat size.

I did see a lot of sectional density info, but I don't believe it computes directly to penetration, does it?

I have a 405g handgun load that departs at 947fps and it penetrates all out of proportion to any numbers you could assign it. Like 13" of seasoned douglas fir. This is a bullet that I suspect has a very poor sectional density, very low velocity, but enough penetration to disrupt the CNS of any animal on the continent. That's my formula for 'killing power'.

If anyone has a bison or huge bear or even a steer that is willing to do some post-mortem pen tests I'll supply the ammo.

I think wound channels are highly overrated. Arrows don't have much of a wound channel but that doesn't stop the animals from dying. Our predecessors killed everything that needed killing with pointed sticks. No huge wound channel there.

But you know that's just me again, I'm kind of a show me guy, and I don't mean the numbers.

Thanks for the effort to systematize all the variables it makes for interesting reading and certainly stimulates the gray cell.

Grizz

El Chivo · Post by **El Chivo** » Sun Oct 25, 2009 4:14 pm

It dropped like a rock and was totally dead

Nice formula, but doesn't take into account how dead you want it.

but seriously...

I think you have to take into account the bullet performance. I've been debating this with myself lately. I am down to choosing between the Barnes 30-30 150 gr and the Barnes .357 140 gr. Because of bullet construction and attainable velocities, the 30-30 bullet won't expand past 200 yards, yet the .357 will expand out to 300 yards (assuming MV's of 2200 and 1800 respectively). In fact, bullet performance of the .357 might be better between 200 and 300 yards, because if it's going too fast when it hits, the petals fold back flat or fall off, reducing the diameter. But if it's going a pedestrian 1200-1500 it will expand into a big flower that will be deadlier than any mushroom in the woods.

This quirk makes me think my .357 would be a better killer than my 30-30 at 200 yards, even though its BTP would be quite low. I'd have a .357 expanded channel instead of a .308 sized pin-hole. Would it penetrate? Barnes says its penetration is excellent. And for short shots, I might lose some petals but would still have a .357+ sized hole with excellent penetration.

To tell the truth I wouldn't mind taking my 1894c out hunting, it weighs a pound less than my 336 and two pounds less than any bolt gun I have seen. But the point it, this particular bullet is constructed so it will expand well when the velocity is low, and bullet weight is quite low, so, do killing power formulas apply?

JohndeFresno · Post by **JohndeFresno** » Sun Oct 25, 2009 4:33 pm

Grizz wrote:it's interesting to see all the calculating and trying to visualize what it means.

I didn't see mention of momentum or meplat size...I have a 405g handgun load that departs at 947fps and it penetrates all out of proportion to any numbers you could assign it...
Grizz

JohndeFresno wrote:That looks appealing to me. Before I start plugging in the formula to the loads I have on a database, I am wondering if there is a way to further refine this formula by adding the meplat into the mix.

I am thinking that a .45 Wide Flatnose (WFN) would hit harder than an old style roundnose, for instance; and that a .30-30 flatnose would have more shock power at the same speed than a pointed projectile (leaving out differences in expansion from the bullet construction, of course).

Grizz,

There's a lot in this thread; but look again - this was my first reply on Pg 1. I agree with you - nobody has yet perfected the formula for stopping and/or killing game; and we can find dozens of anomalies. But at least it's a beginning.

I am awaiting 86er's book; maybe he has come even closer to the magic formula with his research.

Bogie35 · Post by **Bogie35** » Sun Oct 25, 2009 4:47 pm

Grizz, you are correct about momentum. It is a function of weight and velocity, and it is just as important as Sectional Density, and probably more. Penetration is a function of Momentum X Sectional Density.

Of course, as El Chivo suggested, the formula is only useful in comparing cartridges using bullets of similar construction. With higher velocity, a bullet will expand more. Because of this, there is a peak velocity that delivers peak penetration for each bullet. Any increase in velocity beyond this peak will actually produce less penetration (because there will be more resistance from the larger expanded meplat). It's why you will generally get deeper penetration at 100 yards than at the muzzle with an expanding bullet. That's why big slow moving bullets can penetrate incredible distances.

As for the killing power of pointy sticks, animals can certainly be killed with them. I'm sure that vastly more game has fallen to the pointy stick than to all gun cartridges combined. Whenever you perforate vital organs, the result is usually going to be a dead animal.

But a long pointy stick, with its greater Sectional Density, will penetrate further than a short one.

Thanks fellas!
bogie

Grizz · Post by **Grizz** » Sun Oct 25, 2009 5:11 pm

Thanks John I missed that.

There are also issues of how bullets travel thru flesh. The model of the large meplat bullet is hyper-cavitating and having little resistance in flesh, and max momentum penetrating bones. I think it's why the African hunters use the solids on DG, and I include bullets like the piledriver and Young's bullet in the solids category. It definately doesn't expand much in flesh type media, water say. Yet a 223 might penetrate a steel plate that will vaporize hard cast lead. Lots of not necessarily intuitive stuff going on.

I think momentum counts for more than any other quantifyable variable, but I can't prove it. It's my pet unproven theory.

It is interesting and I applaud the efforts of the engineers to quantify all those variables and produce a consistent benchmark from them.

Vince Lupo hit a Cape Buffalo crosswise and lengthwise with Garrett's 540g hammerheads and they penetrated clear through, both directions.

http://www.garrettcartridges.com/lupo.asp

Randy Garrett discusses why this is here:

http://www.garrettcartridges.com/Penetration.htm

How does this impirical information stack up with Bogie35's formula? I'm too too to do the math... but I'm curious, because Lupo's stuff is the real deal.

Curious, Grizz

But a long pointy stick, with its greater Sectional Density, will penetrate further than a short one.

I love it!!! Right up my alley.

JohndeFresno · Post by **JohndeFresno** » Sun Oct 25, 2009 6:58 pm

Grizz wrote: [snip]
Vince Lupo hit a Cape Buffalo crosswise and lengthwise with Garrett's 540g hammerheads and they penetrated clear through, both directions...

...How does this empirical information stack up with Bogie35's formula?...I'm curious, because Lupo's stuff is the real deal.

I don't want to beat the XLS stuff to death, or we'll probably have a reader's revolt here. But here is a sampling of other high power cartridges (with the .223, since you mentioned it), along with the highlighted heaviest Hammerhead load in .45-70. I threw in some mild velocity .45-70 loads for comparison (Trapdoor loads).

Since Bogie35's formula employs Sectional Density as a factor, you can see that it assigns a very high score to the big, heavy bullet.

And here are some stats - from the Garrett site - on the bullets:
http://www.garrettcartridges.com/products.asp

Grizz · Post by **Grizz** » Sun Oct 25, 2009 9:27 pm

Looks pretty interesting and I think Bogie might be on to something from the looks of it. Thanks for the table, it gives me something to chew on. Might be good to stick an AK-47 load in that table to universalize it.

Thanks Guys

Grizz

JohndeFresno · Post by **JohndeFresno** » Mon Oct 26, 2009 12:47 am

Grizz wrote:Looks pretty interesting and I think Bogie might be on to something from the looks of it. Thanks for the table, it gives me something to chew on. Might be good to stick an AK-47 load in that table to universalize it.

Thanks Guys

Grizz

Grizz,

I have some 7.62x39 entries. I added the latest Hammerhead for your benefit, so it is not in the tables that I put online. The standard SKS load (there are several shown) runs about 12.0 TKO, and around 22-23 Bogie TP. A heavy 173 grainer runs more - like the .30-30 170 gr. load.

You can see all the other loads (170+ of them), including the AK-47 / SKS rounds, by clicking on this for a download:
http://www.box.net/shared/4femvtikeg

Jacko · Post by **Jacko** » Mon Oct 26, 2009 2:56 am

Good work on this formula . I'm convinced it's not possible to have a perfectly accurate formula , just look at the answer to the ultimate question in the Hitchhikers Guide to the Galaxy = 42? , there is just to many variables but I reckon it's a reasonable tool and gives food for thought .

This reminds me -there has been a big stink going on in the bowhunting world for a few years now where most bowhunting folks have been converted to the high velocity light arrow craze by the marketing types but there is a growing crew of Traditional types that realise what worked for their Grandfathers will work for them - Sound Familiar .

Dr Ed Ashby a respected bowhunter has been compiling data for years on arrow penatration and the basic results are that slow heavy arrows just like slow heavy bullets are more likely to pentrate bone than lighter faster projectiles of either type . He puts a lot of credence to the sectional density of the arrow and the momentum and very little of impact energy as measures of penetration . Of coarse there is many other factors , I think it was 13 factors , he does use maths and attermpts to prove his findings where a formula exists throughout his study that may help with this formula's development .

Just for interest , I have posted this link - http://tradgang.com/cgi-bin/ultimatebb. ... forum;f=24

regrads Jacko

Don McDowell · Post by **Don McDowell** » Mon Oct 26, 2009 8:38 am

[quote="El ChivoIThis quirk makes me think my .357 would be a better killer than my 30-30 at 200 yards, even though its BTP would be quite low. I'd have a .357 expanded channel instead of a .308 sized pin-hole. Would it penetrate? Barnes says its penetration is excellent. And for short shots, I might lose some petals but would still have a .357+ sized hole with excellent penetration.
?[/quote]

You might want to spend some time dwelling in ballistics calculators to rethink your theory , before you end up out in the woods with a real disaster on your hands.
IF you could get that 140 gr 357 bullet to 2000 fps at the muzzle without damaging something at 100 yds it would be slowed down to 1485fps with a bit over 600 fpe. By the time it gets to 200 yds it'll be doing just a tad over 1100 fps be less than 400 fpe and will have be 16 inches low from a 100 yd zero. At 300 it'll be doing 950 fps have under 300 fpe, and will have dropped 58 inches from your 100 yd zero.

Whoever told you that a 170 gr 30-30 won't expand at 200 yds was wrong.

Grizz · Post by **Grizz** » Mon Oct 26, 2009 8:51 am

thanks for the spreadsheet link. that's good going there. and thanks to Bogie35 for noodling it out. we can stick out pet peeves in there and see how they line up. fun stuff.

Grizz

El Chivo · Post by **El Chivo** » Mon Oct 26, 2009 10:12 am

At 300 it'll be doing 950 fps have under 300 fpe, and will have dropped 58 inches from your 100 yd zero.

Whoever told you that a 170 gr 30-30 won't expand at 200 yds was wrong.

Dwelling on ballistics calculators is exactly what I've been doing. No real-world tests here. However, what I'm saying is that due to new bullet design some of that thinking may be obsolete.

The 950 fps at 300 yards is enough to make the XPB bullet expand, whereas the 30-30 BARNES bullet, which I'm stuck with, won't expand beyond 200 yards, because it requires 1400 fps to expand. According to Barnes.

Yes 950 fps is slow, but it would be like getting hit by a 38 special at the muzzle. Would that penetrate a deer broadside? Sure, at least in one side, and rattle around a bit. It's not going to bounce off. The bullet drop I can compensate for with a tang sight.

So again, which would you rather have, a .357 bullet that expands into a large flower going 950, or a .308 bullet that doesn't expand at all going 1200-1300?

Either way I'm tempted to go for a style of hunting that would produce short shots, i.e., rousting deer from bed as opposed to glassing a distant hillside. But I couldn't help noticing that gray area where my .357 will expand and my 30-30 won't.

Don McDowell · Post by **Don McDowell** » Mon Oct 26, 2009 10:24 am

El Chivo wrote:
and rattle around a bit. It's not going to bounce off. The bullet drop I can compensate for with a tang sight.

So again, which would you rather have, a .357 bullet that expands into a large flower going 950, or a .308 bullet that doesn't expand at all going 1200-1300?

Either way I'm tempted to go for a style of hunting that would produce short shots, i.e., rousting deer from bed as opposed to glassing a distant hillside. But I couldn't help noticing that gray area where my .357 will expand and my 30-30 won't.

You're going to have to throw a minimum of 36 minutes elevation, never mind the wind drift on that dinkus thing, if there's even a 5 mph croswind, into a tang sight on that 357 in the short amount of time alotted in a hunting situation. Lots of luck. With the 30-30 a simple bit of hold over will make a 300 yd shot possible.
You 357 bullet likely won't expand past 100 yds, the 30-30 will expand to 300.
Lots of luck with your hunting but I think you're headed for a real heartbreak.