Cable68; Newton never mentioned Energy.
He stated that Momentum would be conserved.
Momentum has direction it is a vector.
Energy has no direction it is a scaler.
Good luck!

I have two interests in 'stopping power'. Well, maybe three.

Firstly there is the suffering an animal might undergo if it dies slowly. It might be severely wounded but not immediately fatal and lie there suffering for hours or days due a bullet that didn't perform as hoped.

Then there is aspect of losing the animal or having to search for it or follow it.

The possible third would be the animal getting me! That's not good either. (Feral pig or sharp antlered deer).

On differences of day to day reactins on animals; we shoot possum in our parts as they are a pest. One day a possum will just drop over dead and not even close its eyes. On another it will take up to ten shots to kill it! This is with sub-sonic 22LR.

We also shoot feral goat for the same reason. Using a 25/303 but with different bullets and different loadings the reaction of the goats differ hugely. One bullet would blow them apart (including taking out a shoulder but the animal dissappears and can't be found). Another bullet creates a small wound channel making shot placement critical. A third bullet strikes them down like a bolt of lightning. This same last bullet kills turkey dead on the spot but leaves only a small wound channel. A different bullet and gun will blow turkey apart and they will twitch for several minutes! Then my humble little 22 hornet would consistantly drop goats on the spot with side on chest shots. (Then they would go into kicking spasms as they expired).

Of you folks know all about that but this is what complicates the issue.

So, how does one find an answer to the original question?
Is it just collective experience?

quote:

Originally posted by 303Guy:
So, how does one find an answer to the original question? ...

One of the best ways on this Board is to let Mr. Lead Sled(jeffee, never fired a shot without one) or teenScum regale you with their (totally lacking) wisdom and first-hand experience( ).

Then it is very simple to do just the opposite, which will normally always be correct.

Hi Hot Core
Still giving 'em 'sticks'!

I've been thinking about this and it occured to me I don't know how Greenhill's formula works. Can someone fill me in please?

There is another 'formula' that equates bullet energy/momentum to 'optimum big game' and 'optimum varmint' weight. It's to be found on JBM Ballistics Calculations. (Not the formula but the results are given). It does not take bullet design etc into account (I think).

anyone see any missing posts around here?

-just askin'

quote:

Originally posted by DuggaBoye:

quote:

Originally posted by butchloc:
a rabbit vs a train - now thats stopping power

Yep, that rabbit is stopped.

As it a bug on a windshield.

the rabbit will still remain intact,[unless it goes under the wheels ]
but an HV cartridge will blowapart[stop] a rabbit.
Though it has far less energy or momentum than the train.. its stopping effect on the rabbit is no less.

quote:

the rabbit will still remain intact,[unless it goes under the wheels Big Grin]
but an HV cartridge will blowapart[stop] a rabbit.
Though it has far less energy or momentum than the train.. its stopping effect on the rabbit is no less.

That illustrates that momentum isn't everything. Nor is it simply energy. However, in the case of the train, the energy and momentum involved is only that of the rabit being accelerated from zero to the speed of the train at a rate controlled by the 'softness' of the rabits body. It's not gonna get killed!

Perhaps we should be considering 'power' - the rate of energy transfer. That will also take into account the momentum of the bullet. Or perhaps power and 'duration'.

I suspect that if anyone knew the whole definitive truth about stopping power, and was in the guns and ammo business, in a very few years their products would be the only ones selling to hunters in any great quantity.

Until such a person comes along (and I'm NOT holding my breath while I wait for them to arrive), I'd guess we are pretty much stuck with incomplete hypotheses and mandatory compromises.