No, this is not about blowing up a .404 Jeffery with Varget.

MVA = BAM

No this is not the description of the sound of a Motor Vehicle Accident.

BAM = Bullet Area Momentum

This is as simple and real as it gets for settling the sundowner induced campfire debate about which rifle hits African dangerous game harder, but only for those who like to hang their hats on numbers occasionally:

A = cross sectional area of bullet in square inches
M = mass of bullet in pounds (grains/7000)
V = muzzle velocity of bullet in feet per second

BAM = MVA

1. 30-06 180g/.308"/2700fps BAM = 5.17
2. .338 WM 250g/.338"/2700fps BAM = 8.65
3. .375 H&H 300g/.375"/2550fps BAM = 12.0
4. .416 Rigby 400g/.416"/2400fps BAM = 18.6
5. .404 Jeffery 400g/.423"/2400fps BAM = 19.2
6. .458 Lott 500g/.458"/2250fps BAM = 26.5
7. .500 A2 600g/.510"/2470fps BAM = 43.3

The units of this "index" are lbs.ft. sq.in./sec., or momentum X surface area. These could be resorted to represent force X volume per time.

Any interpretation by physicists or engineers would be appreciated.

Kinetic enrgy is definitely not a good measure for correlation with penetration nor the mystical "shock power."

2300 ft.-lbs of kinetic energy can be diissipated in 3 lbs. of water and only raise the temperature 1 degree F.

A 1500 pound cape buffalo would have its temperature raised by roughly 0.004 degree F by absorbing 5000 ft-lbs of kinetic energy.

Any real analysis of animal physiology and bullet construction is "intractable."

Mass, Velocity, size of hole. That covers the basics in all situations.

Momentum is conserved in any collision.
Kinetic energy turns into all kinds of silly sound and fury.

RIP, I'm challenged by such math stuff and only know what a couple buttons on a calculator do. But I do like your thinking on this. In this formula does the "mass" portion give us a reflection of the sectional density?

I'm with Matt on this one seems good but Math�s was not one of my best subjects at school, put mildly I was at the lower end of the class, put correctly I was bloody last.

What about the 9.3x62?

Cheers

Flip

Bakes

You are really getting technical now, I have dropped of the bus a long time ago

Thanks Mike,

I guess common sense and advice from those who have used the calibers on game are always the best guide. Your summary helped clear up a couple of my questions (350 grain in a 375 H&H).

Thanks again,

86thecat

MV/A is just as ridiculous. So is Alphin's penetration index which uses Kinetic energy in the numerator instead of momentum, area in the denominator, then multiplies by the sectional density: PI = (KE/A)SD

Alphin's "Shock Power Index" is a hoot too:

SPI = KE x A

Ray has demonstrated excellent understanding of BAM tabulation.

Saeed and Walter have got a good handle on it too.

But the chap wondering about rain on the buffalo is a bit confused or just being a bit cheeky. I nominate him to insert a telemetric rectal probe into a cape buffalo during the rainy season to monitor its core temperature before and after he shoots it with .577 T Rex, during a light drizzle, to see just how effectively evaporative cooling can negate the 10,000 foot pounds of a 750 grain .585 caliber soft point at 2460 fps.

All such analyses are "intractable." They must be limited by assumptions that pertain to a limited set of conditions, such as "usual bullet weights and diameters" as alluded to by Mike375, who gets it too.

Taylor KO values have some usefulness for brain shooting elephants with solids only, according to the old hands, limited as it may be in significance.

BAM = MV(pi)r^2
TKO = MV2r
so ...

BAM = TKO(1/2)(pi)r

BAM may be the useful soft point index, if Taylor's TKO is at all useful with solids.

I promise not do do anymore indices.

A backdoor rip off of Taylor's KO values. At least the RIP part is correct.

RIP;
MV/A ridiculous? It is the basic scientific expression to start any discussion on penetration ability. It is used by military research and is applicable to all devices, bazookas, depleted uranium and even nondeforming hunting bullets.
Alphin�s penetration index by chance is related to the momentum density MV/A. He uses KE, SD and area because this figures are easy to obtain from published data. If you break down the PI, it is in fact proportional to the momentum density squared. For comparision it is a valuable index.

Even if you limit MVA by assumptions that pertain to a limited set of conditions, such as "usual bullet weights and diameters" , you are on the way into serious trouble. Not boring with calculations, but there are many reports and experiences of my own showing that the big "MVA"s like .600 or 4 bore are not capable to bring down an elephant with a frontal head shot. A .500 NE loaded for 1950 f/s has much more MVA than a .458 Lott, but proven a far less efficiency.

Yeah RIP, what were you thinking mate everybody knows that