|Pattern and Penetration
Rob Douglas takes
an analytical view
|What is more important to
the wildfowler? Patterns or penetration? You need both! You need
sufficient pellet energy to penetrate the feathers and skin and then
to penetrate through muscle, bone and organs. You also need a
sufficient number of those high-energy pellets to ensure multiple
penetration through those vital areas.
In this short article, I hope to show you the value of carrying out
your own, thorough patterning and your own penetration tests as well
as telling you how to do your own tests.
Pattern testing, is, for me, an essential part of my non-toxic shot
studies. Before I carry out any field-testing, I need to know what I
can expect in terms of pellet count for each load/gun/choke
combination that I might use.
I use a system of pattern testing that gives me the maximum amount of
information without being too time-consuming either in implementation
or in subsequent analysis.
My targets for the tests in 2001 were made out of 12 x A3 (420 mm x
267 mm) sheets of paper sellotaped together. This gave me a sheet
approximately 1068mm x 1260 mm which is about 49" x 42". This year I
am using Kraft paper (brown wrapping paper) purchased in rolls of 250
metres x 600 mm.
Wind off lengths of approximately 1068 mm and cut. Two of these sheets
1068 x 600, joined together make a sheet of 1068 x 1200 which, give or
take the odd mm, is the same as 12 sheets of A3 paper to make one
VIKING DIRECT, www.viking-direct.co.uk, sells a roll of the above size
for approx. £25 including VAT.
One roll makes - approx. 117 targets.
The distance from the muzzle to the target was a measured 40 yards. Do
not guess; use a tape measure to ensure the correct yardage.
All my pattern testing has been carried out in the early mornings on
days with no perceptible wind. (Beaufort Wind Scale <=2).
I aim at what I perceive as the centre of the target. The gun was
rested on a polystyrene filled bag when fired at the target.
I fire a ten shot series, one shot for each individual target, as this
number will give a reliable indication of what one can expect.
Each resulting pellet hole on the target sheet is circled in black
ink. A 12 cm (4.75”) circle (using a compact disk) is drawn in what I
judge to be the centre of the pattern. A small dot is placed in the
centre of this circle. A template, 30" in diameter is placed over the
centre of the pattern (using the black dot for alignment) and a black
line drawn around it. Another template, 20" in dia. is then placed
over the centre of the pattern and a black line drawn around it. Thus,
within a 30" dia. circle, I had a 20" dia. circle (concentric) and
also a 12 cm (4.3/4") circle (concentric) in the centre.
First, I count the pellet holes in the "fringe area" …this is the area
between the 20" dia and the 30" dia circles. I ensure correct counting
by marking off groups of five holes at a time and jotting a “tally
mark” for each. I then count the number of holes within the 20" dia
circle; again using tally marks in a notebook. I also draw 12 cm
circles, around any pellet-free areas within the 30" dia circle.
Results are given in a table with the following information: test
number, cartridge, load, nominal pellet count , nominal shot size
given by the manufacturer, diameter of pellet in mm, choke used,
number of 12cm pellet-free patches within the 30" dia circle, number
of pellets within the centre 12cm circle (which is of course included
again when counting pellets in 20" and 30" dia. circles), number of
pellets in the 20" dia. circle and the number of pellets in the fringe
area between the 20" and 30" dia. circles. Thus we can add these last
two and obtain the number of pellets within the 30" dia. circle.
Finally, I calculate the percentage of pellets within the 30" diameter
That is all there is to it – simple!
Once you have carried out your pattern tests and counted the pellet
holes within the 20” and 30” diameter circles you can tabulate the
results and compare them with ten shot series of other shot types and
There are 101 pellets within the
30” diameter circle and 72 of these pellets are within the 20”
diameter circle. This pattern is too tight; unless one is an
outstanding marksman one is more likely to wound than kill. I’ll
define here my definition of an outstanding marksman: one that can
consistently shoot better than 90 x 100 in a demanding sporting clay
There are a similar number of
pellets (100) within the 30” diameter circle, but the pellets are more
evenly distributed. This tolerates greater shooter error and is a
killing rather than crippling pattern.
Both patterns were obtained using the same choke – modified – using a
Mossberg 835 Ulti-Mag.
Both 4mm steel and 3.6mm steel have sufficient energy to penetrate the
vital areas of a mallard at 40 yards; in fact 4.00mm steel will
penetrate the vital areas of a greylag at 40 yards.
However, as photo No 1 clearly shows, steel in 4.00mm using that
particular choke constriction will wound more than kill, as the
pattern is too tight.
By pattern testing, I was able to determine that 3.6mm steel, using
the same choke would give me a similar pellet count in the 30”
diameter circle at 40 yards…but most importantly the pellets would be
more evenly distributed.
For any given choke I have found that the steel patterns tighter the
larger the diameter pellet.
Unless you take the trouble to pattern your gun with the ammunition
you intend to use you will have no idea what pattern density (pellet
count) to expect. It is important not to rely on general Tables, such
as those found in the Eley Shooters diary.
“Choke” is often used to designate the amount of constriction at the
end of your shotgun barrel. It is also used to indicate the percentage
of pellets shot into a 30” diameter circle at 40 yards by that
constriction. I can tell you that, most often, the two are seldom the
same! With one of my chokes for example, three quarter choke (measured
27 thou), I can get pattern densities as low as 45% and as high as 80%
depending on the ammunition I feed that choke.
Out of respect for the quarry you hunt, you should know what patterns
you will be getting. Crippling can be caused by too many pellets in a
concentrated area within a 30” diameter circle as well as insufficient
number of pellets within that circle. You want a sufficient number of
pellets as evenly distributed as possible.
With some of my choke/load combinations, I can get 85% + patterns.
These are commercial loads – I am not a homeloader. I will not use
these ultra-high patterning combinations on live quarry, as there is
more chance of wounding with too tight a pattern.
To obtain the flexibility of matching choke to the variety of modern
non-toxic loads, my recommendation is this: forget your side-by-side
and buy either a pump, semi –auto or over-and-under with a variety of
chokes proofed for high performance steel shot. This will give you the
flexibility to use steel, tungsten-iron, Hevi-Shot as well as the
“soft” metals such as bismuth, ITM and tin and the latest metal alloys
currently in the development stage.
I believe that carrying out comparative testing of different shot
types into a tissue simulant and then investigating the penetrative
performance of those shot types acts as an invaluable guide to the
selection of shot type and size for most quarry species. Of course
this is not the only information required, pattern testing of various
shot types should run parallel with penetration tests as indicated
Telephone directories have been used for many years as a tissue
simulant. Douglas McDougal 2 mentions the extensive use of telephone
directories in his testing. McDougal does not say whether he
pre-soaked his directories. Eley Hawk, who use telephone books in
their penetration tests, do pre-soak their directories. In my opinion
one should pre-soak the directories. If one does not soak the
directories the pellet bursts rather than penetrates the page due to
the low moisture content of the page (approx. 6% moisture). One is,
after all, trying to simulate tissue and tissue contains a lot of
moisture. I fully appreciate that the penetration of pellets into a
telephone directory is a comparative test but pre-soaking to obtain
100% water saturation is, I believe, the nearest layman’s option to
First get hold of sufficient telephone directories!
A note of caution here – for lead shot in diameter 2.8mm and above and
for steel shot 3.25mm and above I use Aberdeen Yellow Pages as these
have approximately 1000 pages. Highlands & Islands directories only
contain 390 pages – only enough pages for small shot sizes.
I remove both front and back covers from each yellow pages directory.
I also remove the first 16 pages, which are a different
weight/thickness of paper than the rest. I also remove a thick card
half way through the directories. Thus I am left only with pages of
the same weight/thickness. (The page thickness, when measured,
appeared to be approximately 65µm)
Each morning, one hour before testing, the telephone directories are
placed in a barrel of water, allowing 100% saturation of the paper
Each directory is removed from the barrel and excess water allowed to
drain. I then open the directory approximately half way through and
hang it over a 20-pound braided fishing line suspended between two
I fire from a measured 40 yards and aim at what I consider the centre
of the directory. The gun is rested on a polystyrene filled bag when
fired at the target:
After each test "session", the directories are taken back to my house
for pellet counting. I simply turn pages until the point where a
pellet or pellets have penetrated a certain page. The page number and
number of pellets (found embedded on that page) are recorded.
After each pellet is accounted for in each directory, I make the
As an example, I show below results from, my own testing. Three
pellets were found on page 509. As the first 16 pages had been
removed.... 509 - 16 = 493. But these are page numbers, so to find the
number of sheets penetrated I divided 493 by 2 = 246.5. I recorded
this as 246 (noted in the results three times as there were three
pellets on the page.)
Fe 4.0mm =Hull Solway Steel No 1 (4.0mm/0/16”) 3” 34 gram
Pb 3.3mm =Lyalvale Super Game Lead No 3, (3.3mm/0.13”) 2 ¾” 42 gram
Pb 3.1mm =Gamebore Buffalo Lead No 4, (3.1mm/0.12”) 2 ¾” 32 gram
Fe 3.6 mm = Hull Solway Steel No 3 (3.6mm/0.14”) 3” 34 gram
Pb SO 2.8 mm = Lyalvale Express Somerset High Pheasant 2 ¾”No 5
(2.8mm/0.11”) 36 gram
Pb 2.8 mm = Gamebore Mammoth No 5 (2.8mm/0.11”) 2/3/4” 36 gram
Fe 3.25mm = Hull Solway Steel No 4 (3.25mm/0.13”) 3” 34 gram
Pb 2.6mm = Lyalvale Super Game No 6 (2.6mm/0.10”) 2 ¾” 36 gram
Fe 3.0mm = Hull Game Steel No 5 (3.0mm/0.12”) 2 ¾” 32 gram
Pb 2.4mm = Hull Three Crowns No 7 (2.4mm/0.095”) 2 ½” 28 gram
Chart No 1 showed the average penetration for each cartridge type
tested. What I was particularly interested in is what I describe as
the penetration profile. That is the variation of pellet penetration
within the shot cloud and whether one could thus estimate the
potential penetration profile for a given load.
It has been demonstrated by Compton & Giblin 3 that individual pellets
within a shot cloud travel at varying velocity, and thus there will be
a difference in the terminal velocity and energy of pellets within the
shot cloud. Examples of differences in leading and trailing edge
velocities and energy are shown in their report.
Where Compton and Giblin illustrated a shot cloud profile as “ a side
on view of the shot cloud in space”, I wanted to show a side-on view
of the penetration of the shot cloud.
They went on to say “The shot cloud profiles offer unprecedented
detail in the quality control information that it can give,
particularly with regard to the pellet energy variation within the
shot cloud. (my Italics).
They also made the point that their studies showed that there was no
single value for the flight time of a given load to a particular range
and that there can be significant differences between flight times of
leading and trailing edge pellets in the shot cloud. Thus there can be
no single velocity for a given range. They went on to show large
calculated differences in the kinetic energy between leading and
trailing edge pellets.
In one example at 40 metres they calculated a difference of 20% in
pellet kinetic energy between leading and trailing edge pellets. This
possibly making part of the shot cloud ineffective.
Unfortunately, the significance of shot cloud profiles and the
variability of pellets within the shot cloud appears largely to have
gone unnoticed by the great majority of shooters.
Most shooters, probably unconsciously, assume that each and every
pellet within the shot cloud has the same velocity and energy value at
a given range.
I have prepared dozens of penetration profile charts based on my
penetration tests. These profiles give a clear indication of the
penetrative potential of various shot types.
To illustrate this penetrative potential, chart No 2. below clearly
demonstrates that the minimum penetration of steel in diameter 4.00mm
is greater than the maximum penetration of lead in 3.1mm.
Penetration of pellets through a wet telephone directory.
Y axis = No of pellets embedded in specified sheet.
X axis = No of sheets penetrated.
I have used these “profiles” to guide me in my shot selection for
further trials in the field.
In my quest for knowledge about the effectiveness of non-toxic loads I
also needed to investigate the effectiveness of the lead loads they
Thus, when my testing is complete, I hope to be able to choose with
certainty the most effective non-toxic load, not only for waterfowl
but for other species, as I suspect that, in my lifetime, there will
be a total ban on the use of lead shot in the United Kingdom.