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Vital Penetration
Robert Douglas

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Almost a year ago, in an exchange of correspondence, a friend asked my opinion of how shotgun pellets kill. 

This was my reply:-

”In my opinion, lead shotgun pellets do not kill by energy transfer by deformation. Let me explain: A bullet, whether a simple hollowpoint lead 0.22 rimfire, or a centrefire semi-jacketed softnose, when it passes through animal/bird tissues, creates enormous shock waves which destroy not only the tissues, through which the projectile actually passes but also adjacent tissue to the bullet’s trajectory. These "shock" or "stress" waves have been photographed and I think the Swedish Cartridge Company Norma published some of these photos in one of their bullet brochures a few years ago.

“The very low velocity of shotgun pellets, whatever the shot material, combined with their relatively small size is not sufficient to cause any shock wave injury outwith the pellet channel other than very minor damage. Evidence for this you can see yourself - all you will see is bruising in the area around the pellet entrance hole. The reduced velocity after entry restricts the shock wave damage merely to a channel of destroyed tissue along the trajectory of each pellet. It is this restriction of damage which means the injury is related only to the muscle and organs penetrated by the channel of each pellet.

“That is why I believe that wet wood pulp (in the guise of telephone directories) is an excellent tissue simulant. Wet wood pulp is very fibrous and in many respects similar to animal tissue. If you examine a pellet extracted from animal tissue you will observe the pulverised, fibrous, tissue adhering to it – a similar occurrence is seen in a pellet extracted from wet wood pulp.

“Steel kills the same way as lead but, unlike lead, it does not deform on impact. In fact, I also suspect, based on my microscopic examination of shotgun pellets, that lead does not actually deform very much on impact (other than when hitting bone) either. I am pretty sure that most of the deformation observed in recovered shotgun pellets is due to the initial ignition set back forces.

“In a nutshell, I firmly believe that all shotgun pellets kill by penetration of vital organs, not by energy transference due to deformation. Steel, by nature of its lack of deformation is simply more efficient in penetration and thus probably kills better than expected, despite its inherent density shortcomings, and certainly better than any ballistic theory or tables would suggest. “

What I wrote was, I believe, simply commonsense. It amazes me that some wildfowlers actually believe that “shock” has something to with killing wildfowl. It further amazes me to have discovered that apparently so few people examine in any detail the quarry they actually shoot – if they did then they would have a better understanding of what actually kills.

Tom Roster (see endnote) in the USA, with the largest lethality database in the world, has frequently stated that, to avoid wounding, one needs a sufficient number of pellets that have sufficient energy to penetrate the vital areas – i.e. brain, cervical and thoracic vertebrae and heart.

More recently, David Leeming of Cranfield University at the Royal Military College Shrivenham gave a paper (see endnote) at the BASC National Wildfowling Conference early in 2002. In this paper, David Leeming gave a really excellent essay on penetration and lethality and I commend all to read it.

In the days when all our shotgun cartridges contained lead, things were somewhat simpler.

One had to decide on the size of shot suitable for the target quarry species and the maximum range at which one was accustomed to shoot. The wise wildfowler patterned his gun with various shot/choke combinations. Now, with non-toxic shot being mandatory in the USA, Canada, much of Northern Europe, England & Wales, there are further considerations.

Not all pellet materials, behave equally. For that matter, neither does lead. Low and high antimony lead pellets behave differently too – antimony being alloyed with lead to maintain better sphericity

Bismuth, Impact Tungsten Matrix, buffered and unbuffered, Steel, Hevishot (Iron, Tungsten & Nickel), Tungsten Iron and other metals currently under development, will all behave differently. With this in mind it is surely our responsibility to pattern our own guns to determine the pellet count at the ranges at which we habitually shoot. In a previous article of mine in Wildfowling International I describe how to do this.

Thoroughly pattern your gun at the range at which you normally shoot. (I pattern my gun at ranges 30-45 yards) Once you know how many pellets you averagely get within a 30 inch circle with the gun/cartridge/choke combination that you use, it is time to consider the SIZE of the quarry you shoot.

In the USA, CONSEP - Co-Operative North American Shotgunning Education Program have produced a chart (see endnote) that recommends the appropriate steel shot size, pellet count for various quarry species within various range windows. This chart is based on the literally thousands of autopsies carried out on wildfowl in which the range at which the shot bird was known.

Many wildfowlers have only a general idea of what constitutes the vital target area of the variety of quarry they shoot. Additionally, in some of the literature, erroneous or confusing information has been given. Some writers and researchers refer to VULNERABLE areas, others refer to VITAL areas and, unfortunately, they often use both terms in the same paragraph without distinction.

This is not simply a matter of semantics. There is of course a fundamental difference between vital and vulnerable: "VITAL” is ESSENTIAL to life - and if a vital areas are penetrated it is almost certainly dead. “VULNERABLE” simply means exposed to potential harm. Therefore being inconsistent in terminology leads very easily to confusion or misunderstanding. 

In the literature, time and again, one sees reference to the “vital” area of a mallard as 20 square inches. This is surely incorrect. Cochrane (see endnote) correctly describes the vital area of a mallard as 12 square inches.

Doubt this? Look it another way……Take out a mallard from your freezer then measure the approximate broadside surface area (i.e. you are measuring the defeathered, eviscerated, headless, wingless, & legless duck) Trying this yourself you can will discover that you get something in the region of 20 square inches. Cochrane’s lower figure was, I believe, measuring correctly the VITAL areas i.e. those which, if penetrated by a pellet, would certainly kill.  My wife and I took the trouble to measure the VITAL areas of a considerable number of my most common wildfowl quarry species, last season. Our measurements showed that the vital area of teal was 4.9 square inches, for widgeon 8.2 square inches and for mallard 12 square inches. These measurements are the average values for male and female combined. The vital areas measured were brain, cervical and thoracic vertebrae and the heart. 

I have found that if one or more pellets penetrate THROUGH one or more of these VITAL areas the quarry will be instantly killed. Failure to penetrate the vital area will not result in instantaneous death and pellets penetrating “vulnerable areas” (a broken wing bone will terminate flight) may result in bagging but only at the expense of wounding first. Pellets penetrating non-vital areas such as the gut will only result in wounding and a lost resource.

The synergistic effect of two 4.00MM steel pellets penetrating vital areas of the greylag goose ensured instant, dead-in-the-air death.

At all ranges, whether short, say 25-30 yards, or long, 40-45 yards, we should each get to know what our gun can and cannot do by carefully patterning the gun. Please do not assume you will achieve the same pellet density at any given yardage with the same load of bismuth and ITM – you will not. Do not assume that small steel shot, less than 3.6mm in diameter will pattern tighter than lead or bismuth – it may not.

Patterning is tedious but there are no short cuts. Take time to examine your retrieved quarry – was it instantly killed or merely wounded before despatch? What was the range at which you shot? Take time to practice judging range accurately. Instead of taking a longer or high “sporting” (?) shot, take pride in your marshcraft and take the shot at modest range when BOTH penetration through vital areas and pellet density is at its optimum to ensure instant kills.

As wildfowlers and conservationists we must do our very best to ensure that not only do we bag what we shoot but that the highest possible component of that bag was killed instantly.


Robert Cochrane, 1976, Wildlife Monograph No 51, Crippling Effects of Lead, Steel and Copper Shot on Experimental Mallards. 

CONSEP Chart 1999: http://dnr.state.il.us/waterfowl/files/pg20pdf and the 2001-2002 chart http://wildlifedepartment.com/waterfowl.htm 

David Leeming, BASC National Wildfowling Conference 2002, Shotgun Characteristics for Effective Lethality. 

Tom Roster,Sporting Clays & Wingshooter Magazine, December 1998 Patterns VS. Penetration, Part one, pages 22-24, 26, 28, 30-31. And Part two, January 1999, pages 38-39, 76-79. 


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