Air
Rifle Ballistics

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RWS Model 54 recoil-less spring-piston magnum test
After years of successful
hunting with the .22-cal side-lever RWS Model 48, I finally decided to try its
recoil-free variation
—the Model 54. I had resisted because the M-54 anti-recoil
mechanism seemed like a needless complication.
One of the most notable qualities
of RWS air rifles is their legendary reliability; why complicate that, I
wondered, with a gimmick?
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Boy, was I wrong!! The instant after the first shot I
discovered an amazing fact: my sight-picture of the target remained rock-solid
throughout the shot!
With my M-48, the sight picture would always jerk off the
target or even momentarily black out due to recoil motion. Maintaining a steady
sight picture
had two immediate beneficial effects.
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First, it let me see where I had hit (or missed) my
target. With the M-48 (and all other magnum powered spring-piston air
rifles) the recoil causes
the rifle to move enough to knock ones view
off—and even sometimes to result in image black-out. (And what a surprise at
that first shot to keep
seeing a rock-steady target!)
And second, by being able to view the target
uninterruptedly, I was able to notice my post-shot barrel motion. I discovered I
was sometimes waving
the barrel right after the shot; was I also waving it during the shot? I was—thus answering the question of why, sometimes, I
just couldn’t get on target.
This is such a useful effect, it seems to me
that practice with a Model 54 might do a lot to cure wandering magnum
marksmanship!
Air gunners who use PCP (pre-charged pneumatic) rifles are
used to this advantage. The mass of the compressed air that squirts out their
pellet is
too low to cause much of an “equal reaction” (recoil). The mass of the
piston and spring of a springer are enough to cause a significant recoil.
Because the exit pupil of a telescopic sight (the shaft of image light coming
out of the scope) is quite small—usually only about 5 mm—it doesn’t take
much
movement to misalign the exit pupil with your eye pupil (itself 2-6mm in
diameter), resulting in loss of
the sight picture.
But PCP rifles require a lot of supporting equipment—a
scuba tank of compressed air, fittings, tubes, etc. And leaks are a problem. The
big advantage
of spring piston rifles is they sit quietly in the back of the
closet. When you are ready to shoot, you pull then out, cock them—and shoot.
Nothing could be simpler.
The Model 54 is one big gun. You really must have a sling
to carry it around. A big gun deserves a big scope, and I used the RWS 4-12X 50
telescopic
sight with one- piece rings. The ring has two anti-creep pins—a real
necessity for all springers . The
wider 50mm aperture
gives a larger exit pupil meaning it is easier to get a sight-picture when you bring the gun to the ready, e.g., 6.5mm at 8X magnification—30%
greater
than 5mm at 8X for a 40mmm aperture scope. The extra amount of light the
larger aperture receives is not enough to make any practical difference. |
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And it’s a powerful magnum. I measured 22 ft-lbs out of the
box using RWS Superdome pellets. This results in delivering a whopping 8 ft-lbs
to
the target at 50 yards. Eight ft-lbs is more than enough to humanely take
most small game--crows, rabbits, woodchucks, squirrels, etc., with well-placed
shots.

Sighting in at 50-yards keeps the pellet within the “natural” zero range (within
±2-inch rise/drop). Maximum effective range is 57-yards. The trajectory
and
energy of the SuperDome (pink squares) and the Super H Point hollow point
pellets are virtually identical—take you pick. Although as an air rifle
hunter, I naturally trend toward
round-head pellets because of their generally superior ballistics. However, the Super H Point
(a modest hollow-point)
gave me astonishing accuracy (see below).
The RWS 4-12 X 50 scope has military (marked) stadia, giving the illuminated
crosshairs reference
points for how much to aim lower or
higher at distances different than your zero
range, and an illuminated reticule. I wasn't wild about this scope, packed
with so many features
except good optical performance. |
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Many air gunners focus on air rifle velocity, believing
this to be a measure of air rifle power; it is not. Velocity is proportional to
energy and
inversely proportional to pellet mass. The heavier the pellet,
the lower the velocity from the same rifle. Here is the velocity graph of the
.22-cal.
Superdome pellet—846 fps at the muzzle, coasting to 500 fps at 50
yards.
 Because of the "velocity race,"
manufacturers usually use the lightest pellet in order to achieve the highest
muzzle velocity. And it is true that
light pellets usually post impressive
muzzle velocities, but they shed energy and velocity rapidly. Some rifles
(particularly in .177-cal.) may obtain
higher energy from a heavier pellet than a
lighter one. A heavier pellet (like the Superdome) will lose energy and velocity
more slowly. By 25-yards
they will generally exceed their lighter brethren in
both factors. And heavier pellets almost always have superior ballistic
coefficients, thus being
less affected by crosswind.
Shown below are the velocities of three pellets of different weights fired
out of the same gun. Note how the fastest pellet out of the blocks is the
lightest one. But by 30 yards it is already the slowest pellet! At 50 yards, the
pellet with the slowest muzzle velocity has held on to it and is now the
fastest
at that range. Energy at range follows a similar pattern except that in many
rifles, the heaviest pellet often produces the most energy at all
ranges—and
loses it the least quickly as well. That is why air rifle hunters tend to select
pellets beginning with the heaviest one available,
and then backing off of weight to find the
compromise that gives the best combination of sight-in (±2-inch) range and
downrange energy.
 Cocking the
side-lever of the M-54 requires a hefty pull. As with all magnum-powered
springers (and particularly with air-spring rifles)
you should be sure you have
the strength to manage the cocking effort. (A little practice goes a long way to
making it easier.)
Towards the end of the cocking stroke, one can feel the
anti-recoil mechanism being engaged. The safety sits at the base of
the
receiver, handy to the thumb. It is resettable without re-cocking.
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The trigger set point is adjustable, and I backed-off the
factory setting just a tad so that the M-54 fired when I thought it right to do
so; not
when I jerked the trigger to make it do so.
The discharge sound is solid grunt -–“kruck”-- rather than
a bark. Missing a woodchuck one a windy day, I saw for the first time by the
dirt
the pellet kicked up how much Kentucky windage I had to apply for the next
shot. A continuous sight-picture--what a boon to improving my
yield of hits to
misses!
Perhaps the biggest pleasant surprise was the field
accuracy I was able to obtain after some practice with the Model 54. Its weight
certainly
reduces jitter, so I shot in the difficult offhand stance. The first
five-shot pattern would barely fit inside a dinner plate! Darn! I muttered to
myself,
I know I can do better. So I screwed up my concentration--and shot a 1 X
2-inch pattern! That’s the best I’ve ever shot, offhand at that range--
and
amply demonstrates that with a gun that is inherently accurate, marksmanship is
largely a matter of concentration on the task..
 Shooting the
Model 54 has completely changed my mind about its anti-recoil feature. It is not
a gimmick;
it’s a splendid improvement that lets the varmint hunter really
improve his shooting—and right away. He also
immediately gets a
much better chance of “bringing home the bacon,” instead of bringing home
stories about
“the one that got away.”
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How to choose Air Rifle Caliber
© 2002, 2003 by Tom Holzel, with Jim Baumann
With premium air rifles costing as much as they do, figuring out what
particular brand and model to buy can be
quite confusing. On what do you
base your choice? The first step is clearly deciding how much money you can
afford to spend. This will determine the quality level, and the features of the
gun. After deciding this, the next most
important factor is to chooser the
correct caliber for the gun's intended purpose. If you are going to own
only one gun,
this can be an agonizing choice. Here's the approach I used
to decide between a 5mm and .22-caliber Theoben
Eliminator rifle for hunting in
southern England.
As a long time air rifle crow hunter in the U.S., I recognized that to
English farmers, hares, not crows, are more of a
nuisance, so they would be the
varmint of choice in my new home in Oxfordshire. With crows, long range is
more important
than high power, so for that task the longer reach of the 5mm
would be the obvious choice. Would that caliber also be the
optimum for fur
bearers? When I examined the published performance I was puzzled by the
ballistic data given the Eliminator
on the Theoben website (http://www.theoben.co.uk/). Their
highly regarded 5mm rifle is listed as having a muzzle velocity of 880 fps,
with
840 fps remaining at 50 yards. Energy figures are quoted as being 24.5 ft/lbs at
the muzzle and 22.4 ft/lbs at 50 yards.
These figures indicate the Crosman
Premier pellet used loses only 4.5% of its velocity over 50 yards -- yet drops
by 23% the
next 50 yards. The .22-caliber figures were equally confusing.
There are two ways to determine the trajectory of a pellet: Empirically on
the range -- this is the most reliable method--or theoretically
(and much more
rapidly) by means of a ballistics software program. To help me clear up
the issue, I bought an air rifle ballistic
program developed by Jim
Baumann of Lame Rabbit Software (Note: Jim is apparently no longer in
business). Let's see how the two
calibers fare (at least on paper).
To use ballistic software, one needs to know (or find out) the correct
ballistic coefficient (BC) of the pellet being tested and therein
lies the rub.
The BC of a pellet is an extremely complex
function that changes depending on a pellet's range and velocity.
A pellet can have an excellent BC at one muzzle velocity and at one
optimum range--and then flop miserably as the velocity is
changed, or the
measuring range altered. In the case of the superb 5mm Crosman Premier
recommended by Theoben,
Jim Baumann has measured its BC as is high as 0.040 at
25 yards, but more commonly at 0.0308 at 50 yards. The big
advantages of
the 5mm Premier pellet are that of high, repeatable quality and that it has a
high BC. But -- unlike many other
pellets--it maintains its BC to well
over 900 fps. We use 0.0300 at 950 fps for the maximum usable power of this
pellet.
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To complicate matters even more, BC varies from shot-to-shot! Below is
a sample of a series of shots measuring BC of a
5mm Crow Magnum (Eliminator)
with chronometers set at 10 ft and 45 yards from the muzzle.
To determine maximum usable range, the shooter has to decide how many inches
of rise above the telescopic line of sight is he willing
to aim at intermediate
distances. With 12-lbs-ft rifles this is usually 3-inches. But with a FAC
rifle this is usually 2-inches -- or less.
And the shooter must determine
his own personal field marksmanship. Then, knowing the pellets BC, ballistic
software lets
us plot the trajectory for different sight-in ("zero") ranges.
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Chart 3 shows the trajectories of the two calibers when sighted so as to
result in a rise of two inches, each at two different power
settings.
The lower power settings are those which the Theoban website
says result in the highest accuracy; the higher settings are those used by
many
American varmint hunters for maximum effectiveness. Recognize that with all
mechanical devices, (your car, for example) extracting
more power results in
more rapid wear & tear.
Notice (chart below) that if we also allow two inches of drop, we can
achieve an absolute maximum theoretical range (blue line) of the two
calibers
of 63 yards for the .22-caliber, and 72 yards for the 5mm. But,
accuracy will probably hold up over the farthest reaches of our neat graphs only
as wishful thinking.
What this means is that while ballistic computer plots of air rifle rounds
are useful as starting points, complex second-order aerodynamic
factors begin to
dominate at the higher ranges and velocities -- that is, much beyond 60 yards.
Also, wind deflection alone can double group
size from 50 to 70 yards.
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But wait -- can I even hit the 3-inch "kill zone" of my target out to 70
yards? Certainly not from a standing position. However, when shooting
hares,
I will almost certainly be either sitting, or probably even lying down.
But even using a bipod, will any air rifle shoot that accurately out to 75
yards?
In the field I can realistically put three out of four shots inside
a 2-inch circle from the seated position at 50 yards. If the pellets'
flight continued
perfectly, that would result in a 3-inch circle at 70
yards. But perfection never happens.
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Robert Beeman, (founder of Beeman Precision Air Rifles in
California) believes that down-range pellet instability is primarily caused by
two factors:
First, any random tipping of the pellet as its skirt loses final
contact with the edge of the muzzle; and second, the imperfect distribution of
the pellet's
mass about its spinning axis. In both cases the pellet can
begin to wobble more -- and then less -- and then more again -- during its
flight.
This wobble becomes more acute the faster and the further the pellet
travels. Combine this with the minute shot-to-shot variations of power and
it
becomes easy to see why even with the best high-powered, long range air
rifles, perfection is unattainable.
This brings us to the next consideration -- "terminal ballistics"--the effect
of the pellet on the target.
Chart 5 shows us that the energy the two rounds carry at two different power
settings. The reason the 5mm loses energy slightly faster is that its
ballistic
coefficient (BC) is less -- 0.0300 vs. 0.0340 for the .22-cal.. This is
almost always the case, that larger pellets have better BCs than
smaller
ones. In the case of the Premier, Jim Baumann believes the cause has to do
with a pellet's length which has been optimized for long range.
What is interesting about this chart is that, although the 5mm Premier pellet
leaves the muzzle with more energy than the .22-cal H&N Barracuda,
because
the Barracuda has a slightly better BC, loses energy less rapidly. But think on
this: By increasing power above the Theoben optimum,
how much range and extra
energy are we really gaining? |
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Yet it is not energy but "lethality" that we seek. What is the
difference? Firstly, let us go to the sight-in range of 60 yards. Of
course the 5mm
round is traveling a lot faster than the heavier .22. And the
equation for energy is well-known: E= mv2/2. In other words,
increasing the velocity
just a bit results in a whopping increase in energy. But
there's a major snag.
In my experiments shooting into an animal flesh simulator (Ivory soap), I
discovered that a .177-cal Hobby pellet penetrates 7.5 to 8-inches
when carrying
15 lbs-ft of energy. A .22-cal Hobby pellet only penetrates 5 to 6 inches with
the same energy. The reason for that should be clear.
The .22-cal pellet must
clear out a wider wound channel per inch of penetration. Indeed, with these
experimentally derived figures, the .22-cal
creates a short, fat wound
channel with a volume of 0.19 cubic inches, while the.177-cal pellet creates a
long skinny wound channel of 0.185
cubic inches -- in other words the same wound
channel volume -- an amazingly close experimental confirmation (and a great
advantage of
using Ivory soap for these tests).
Now here's the high-velocity catch: Shooting both of these pellets into a
critter with a diameter of only 2.5-inches means both pellets will exit
the
animal -- and carry with them unspent energy. But the .22 will have dropped
off half its energy in this example. Since it can penetrate
5
inches, and exits after half that distance, so it has used up half its energy or
7.5 lbs-ft. The .177-cal pellet can penetrate three times as far,
so it will
exit with 2/3rds of its energy intact. It will have dropped off only 1/3 of its
energy, or 5 lbs-ft. Thus the fatter .22-cal pellet will have delivered
50% more
energy to the target; energy that is, of course, more destructive, or more
"lethal." (Of course, these depths are theoretical in that they
apply to Ivory
soap which may or may not be an accurate flesh simulator. If the pellet
hits bone, a lot more of its energy is transferred to the animal
-- in most
cases, all of it.) But there's more to the energy story.
This over-penetration gave me the idea for a real hollowpoint pellet -- an
egg cup design that would really open up. The result was Dr.
Beeman's
Crow Magnum hollowpoint pellet. It will double in caliber
inside a varmint and almost never exits the critter. However the 5mm Crow
Magnum
hollowpoint BC is only 0.0263 at 900 fps. So you will have to experiment
to see if the higher lethality of the Crow Magnum pellet is worth its
slightly
lower efficiency.
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Jim Taylor, a world famous big game hunter, wrote in the November 1947 issue
of American Rifleman that his experience with the
E=mv2/2
high-velocity equation did not comport with his extensive personal experience --
so he made up his own lethality index --
the Taylor Index. His equation
is:
TI = (grains*velocity*caliber)/7000.
Note that velocity is really given short shrift in this equation; it is no
longer squared. Because Taylor was using really big guns,
his numbers come out
big -- or, put the other way round -- when we plug in air rifle values, they
come out very small. So I modified the
Taylor Index and call it the Taylor
Value. Instead of dividing by 7000, I divide by seven.
Using that modification, we can calculate the Taylor Value for the Eliminator
5mm and the .22-cal pellets at 60 yards. They are:
TV5mm60 = (14.3grs * 729fps * .20-in)/7 = 292
TV22cal60 = (21grs * 601fps * .22-in)7= 422
Wow -- the .22-cal comes out 44% more lethal at 60 yards than the
5mm. Now we can see where the .22-caliber's fur-punching
reputation comes
from!
So here's the question I have to answer for myself:
| |
5mm |
.22-cal
|
Delta |
| Max Range (yds): |
63 |
57 |
22% in favor of 5mm |
| Taylor: |
292 |
422 |
44% in favor of .22-cal |
| Pellet Pressure* |
541 |
473 |
14% in favor of 5mm |
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What is more important -- 22% more range or 44% more
lethality? [New commentary] Or a 14% higher "Pellet Pressure"?
*(Pellet Pressure is
the energy at the target divided by the cross-sectional
area of the pellet. For example, 300PP is required to punch through the
folded wing
feathers of a crow.) Notice that the 5mm pellet has a better PP
(penetration) than the .22. This is one reason why in America, the 5mm pumped
up
to achieve 950 fps with the Crosman Premier pellet has developed such a
very strong following among varmint hunters. It results in a high
sustainable accuracy at the greatest ranges, with sufficient lethality to
do the job. Future experimentation will reveal which of the two pellets
create a
larger wound channel. It will be very interesting to compare the wound
channel volume of the Premier vs the Crow Magnum pellets
as well.
(After all that work to determine efficacy, it still remains a matter of
opinion and personal choice!)
Chrony ballistic software Before you compute pellet trajectories, you have to measure the
velocity at two distances--typically zero and 35 or 40 yards. Shoot five pellets
through the Chronograph at zero yards distance, then five pellets through it at
35 or 40 yards. Note that the Chrony does not require the white
plastic sun
shields unless the sun is out and brilliantly clear. Even a
hazy sun won't give good readings with the shields in place. If you plan
on
doing a lot of testing, buy two Chronys and shoot through both of them at the
correct distances, at the same time. Then average the velocities,
throwing out
any fliers.
The Chrony ballistic software is a very awkward and buggy product
that can be used only after much fiddling about. But then it is extremely
useful.
Here is a short-cut that works just fine. You don't need a
PDF converter to view this program, although it may sometimes be necessary
to view
certain documents and
files. Struggle to get the toolbar header to appear. Under
"Project," click to the "Trajectory Table" at which the screen (below) will
open--except there
won't be any numbers in the fields.
Fill in the variables in the screens marked "Range," "Sight-in," "Target" and
"Bullet." In order to fill in anything, you have to first erase
(not overwrite) anything in the blanks. Then (and this is the secret
to making this product work) estimate your pellet's ballistic
coefficient,
and enter it in the B.C. field. |
You will also have entered a velocity value for either zero yards or 5
yards. Where the chart says "Velocity, 717fps" was where I
entered the average
velocity at that range of 5 to 10 pellets. You will also will have changed the
"Range" distances to 100 yards in 5 yard increments. |
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Now, each time you enter
an estimate of BC, all the chart figures change
(or hit "Compute" to make them change) (Except the zero yards figures).
Then look at the
"velocity (fps)" values
for the other, more distant ranges you used to test your pellet
with the Chrony chronograph--say the 45 yd value.
It will change with each new guess of BC. When the velocity of the table
at 40 yards changes to the figure you obtained in the
field--voilá--you will have
correctly guessed the pellet's BC.
Now the rest of the table's figures will also be correct--energy, velocity,
drop, etc. for all distances. Now you can
copy the drop figures
to Excel to make a trajectory chart.
Since a pellet's BC varies with its velocity and range, you can see that BC
is not anything intrinsic to a pellet, such as its mass. Rather, BC
is an
abstract factor used to make trajectory calculations come out
right! The actual Chrony trajectory computation is quite accurate--within
1/2 inch
as far as I could tell (and even that difference is just as likely
to be mine and not that of the program). For a more detailed explanation of BC,
check out this
informative website.
_____________________________________________________
Tom Holzel is author of The Air Rifle Hunter's Guide,
Velocity Press, (Sold by Beemans and Crow Busters). He was hunting editor
for
American Air Gunner magazine and has written numerous air rifle
reports including on the Theoben .22-cal Crow Magnum and a series of RWS air
rifles.
Has most recent article on
air guns was with John Zent, Editor of the NRA magazine American Hunter,
August 2002.
Jim Bauman is a professional ballistician and veteran air rifle
user. He is the author of the "Lame Rabbit" air rifle software program
used to produce the data and charts for this article.
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For an outstanding treatise of various aspects of air rifle
ballistics--particularly internal ballistics--see this excellent
site: http://www.arld1.com/
For a tremendous trove of airgun knowledge, see Dr. Beeman's comprehensive
web site:http://www.beemans.net/ .
See in particular Dr. Beeman's
article on Airgun ballistics at http://www.beemans.net/airgun%20ballistics.htm.
For a catalog of ballistic source material, see: http://www.goneshooting.co.uk/Ballistics.htm
A neat air rifle website is the British air rifle Review Centre.
For more air gun hunting, see: http://www.airgunhunters.com/index.html
Finally, another extensive listing of air gun material: http://www.airgun1.com/listings/adult_precision_air_guns.html
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Scope Recoil Creep One of the most pernicious problems of magnum powered spring-piston air
rifles is the effect their towel-snapping recoil has on the
mounting of the telescopic sight. Here is a photo of my trusty RWS .22-cal Model 48
showing the channel the scope stop screw
carved into the scope rail.
 Admittedly, this mounting has held up for about 4 years of shooting.
But when it went, it went quickly. Suddenly I was missing
40-50 yard woodchuck shots that I had routinely hit before. The simplest repair in
this case would be to unscrew the rail and
reverse it. (Be sure to drill a
lubrication hole.) But I bought a new rail from RWS ($39.95) However, the
screws have been racked
in so tightly, I will probably have to have them
drilled out. My Kodiak scope mount is also starting to show some wear
(Photo below). Needless to say, all screws should be set with full-strength
(blue bottle) thread
lock liquid ("Lok-Tite"). Be sure to clean the
threads with alcohol first
(Use vodka or gin if you don't have denatured alcohol.) One essential
point: Do not try to save weight by
buying scope mounting parts whose screws
or screw
threads are made of anything but steel. I have not found any
scope
mounts which use alloy screw threads--male or female--that will
hold up; they must be steel. (but the hardware that holds the scope
tube
can be aluminum.) Also, one-piece scope mounts seem better suited for
the recoil shenanigans of spring piston air rifles.
The scope tube can slide perniciously, too. Wrap a piece of "Scotch"
(cellophane) tape around the top of the scope tube right next to
the scope ring. Check the edge of the tape frequently to see if the scope
has moved--especially if you notice your marksmanship is
slowly deteriorating.
If you can't get the scope tube to stop slipping, insert a very slender strip of
Emory cloth between scope and ring.
The bite of the Emory cloth grit will hold
the scope fast. A third source of creeping inaccuracy is the receiver of the rifle coming
loose from the stock. It should not, of course--rattle the
tiniest bit if you
jiggle it. One sign of a loose receiver is a tight group marred by 2-3 flyers
(instead of just one.)
Here is the recoil dent worn into the Kodiak scope mount. (Red arrow).
http://www.airgunsofarizona.com/beemanscopes.html
http://www.sportsmatch-uk.com/products.html
http://www.reliablehost.com/bsquare/airgun_1.html
http://www.theoben.co.uk/frameset.html
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Expanding Air Rifle Pellet
So-called hollowpoint pellets have been around for along time--but none of
them expanded at all inside target critters. None, that is,
until the Beeman
Crow Magnum hollow head pellet. Here is a photo of a .22 Crow
Magnum taken out of a red squirrel shot at 37 yds
with a 21- ft-lbs RWS Model
48. The pellet entered the squirrel above his front leg and was recovered
pressed up against the inside of
the hide of his rump. (In other words, the
pellet had traversed most of his length.) As the photo shows, even at that
range, the pellet did
expand to increase the diameter of the wound channel.
Good News! A cache of
The Air Rifle Hunter's Guide, 4th Edition (the final) has been found. $35 ea, U.S.
postage included.
Click here for more
info on this hunting classic.
Send checks to Velocity Press, 3 Durham St. Boston, MA 02115.
First Come, First Served. Email to ascertain remaining
availability to
THolzel@gmail.com.
August 2010: The Blue Book of Airguns, eighth edition is
just out now. This famous series is an exhaustive compilation of every
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phone: 800-877-4867.
www.bluebookinc.com
Robert Beeman Ph.D.
Airgun Information International
PO Box 516
Healdsburg,
California
95448-0516
USA
_______________________________________________________________________________________________________
Ballistics of 3 RWS Pellets
Comparison of .22-Caliber HyperMax, SuperPoint Extra & SuperDome air gun
pellets
Rev 18 Sept 10
The RWS HyperMax is a lightweight (9.9 grain) pointed pellet that looks
identical to the 14.5 grain SuperPoint. It is advertised as offering 25%
more velocity, a selling factor that must be examined closely to see if that
is really what you want. I compared those two pellets to my favorite
RWS
hunting pellet, the 14.5 grain SuperDome.
[Insert Photo]
Let’s look first at the advertising claim of the HyperMax velocity
advantage:

The muzzle velocity of the HyperMax pellet is 22% higher than that of
its heavier twin in this air rifle with 16 lbs-ft of energy.
But notice that
by 35 yards its speed is equal to the SuperPoint, and drops faster
thereafter. The SuperPoint starts the slowest (690 fps)
and at around 30
yards overtakes the others in velocity. But the difference between the two
heavier pellets is very slight and could easily
exchange rank in different
air guns.
For hunters, pellet energy at the target is a much more important
factor than speed (except that higher velocity does mean a
flatter
trajectory). Here is the energy comparison.

Note the SuperPoint pellet starts out with the least energy—15
lbs-ft--and loses it to air resistance the least quickly. At 40 yards it
begins
to edge ahead of the SuperDome. But again, the difference between the
heavy pellets is slight. The HyperMax energy at 40 yards is 6 lbs-ft
vs 9
lbs-ft for the SuperPoint. 22% greater velocity, but 50% less energy is the
HyperMax trade-off when used for hunting.
(Note: The graph symbols do not fall smoothly on the curves due to rounding
errors of the ballistics program)
But, the HyperMax energy situation is reversed in less powerful
air guns, see LP8 results below.

Here is a comparison of the trajectories of the three pellets. The vertical
scale has been highly exaggerated to show the differences
more clearly. Note
that while the SuperPoint and the HyperMax both strike the bull’s eye at 50
yards from the same gun, the
HyperMax trajectory rises to only 2.4 inches at
30 yards while the SuperPoint climbs to 2.6 inches. The SuperDome crosses
the line of sight at 47 yards. This is because its Ballistic Coefficient
(BC) is worse—0.015 vs 0.018 for the SuperPoint.
The SuperPoints also hit the 50 yd target 2 inches higher than the other two
pellets using the same zero setting.
The lightweight Hypermax has a BC in this gun of 0.010. Ballistic
Coefficient is a measure of the efficiency of the projectile
(pellet)
traveling through the air. Heavier pellets generally have a better (higher)
BC and are less effected by cross wind.
On a windy day not well suited for
hunting accuracy, the HyperMax would be off by as much as a foot while the
other pellets
were off by a few inches.
The trajectory plots show the main HyperMax advantage—a flatter
trajectory at short to medium range. Its greatest advantage
will be at
shorter ranges in less powerful air guns and in still weather. It is an
excellent pellet for air pistols target competition,
and possibly for short
range pest bird control.
Here in a nutshell is the trade-off of weight vs velocity. These are
graphs comparing the .177-caliber HyperMax and the
SuperPoint Extra pellets
shot out of the RWS LP8 pistol:
  It is easy to see the higher velocity of the HyperMax—32% in this case.
But here is a really surprising effect. The HyperMax also
has the most
energy in this low-power situation! The LP8 pistol just can’t get the
heavier SuperPoint pellet going. With the longer
barrel of a magnum air
rifle, this situation is reversed with the lighter pellet already out
the barrel before it has extracted all the
energy of the propelling column
of air.
 The much flatter trajectory of the HyperMax (Blue line, compared here
against it lookalike stable mate, yellow line, the SuperPoint Extra)
makes
it the clear pellet of choice for indoor short-range target shooting.
One major irk for me was the platter in which the HyperMax pellets are
sold. It was impossible for me to set this artistic marvel down
outdoors
without spilling pellets (But it probably works fine on a table or bench
indoors). My advice: dump the pellets into a standard
pellet tin and be done
with it.

No matter how delicately you set the HyperMax pellet tablet down, pellets
leap out and escape to the ground.
By these accounts, for hunting purposes the SuperPoint outperforms the
SuperDome; it has the same down-range energy,
it has a flatter trajectory.
Yet I prefer the latter for most hunting. Why? Let’s take a closer look at
the ballistic figures.
|
SuperPoint |
|
SuperDome |
|
HyperMax |
|
|
14.5 gr |
Std Dev |
14.5 gr |
Std Dev |
9.9 gr |
Std Dev |
|
687.3 |
12.52138171 |
715.1 |
3.707425 |
853.1 |
7.86117 |
|
669.9 |
4.4% |
717.3 |
0.8%!! |
848.1 |
2.5% |
|
696 |
|
710.8 |
|
832.2 |
|
|
700.8 |
|
715.3 |
|
847.9 |
|
|
698 |
|
721 |
|
844.9 |
|
|
Average |
690.4 |
|
715.9 |
|
845.24 |
|
|
Delta V |
-22% |
|
-18% |
|
|
|
Shown here are the velocities of five shots for each pellet at zero
range. Note that I alternated pellets at every shot, shooting
a different
one after each shot to even out possible accumulating variations of rifle
power. The five SuperPoint shots have
a maximum velocity difference of 4.4%.
The SuperDome an incredible tight 0.8% (which is pretty amazing). It’s
roughly the
difference between a two-inch group and a three-inch group at 50
yards. Thus for me in that air rifle, the SuperDomes are
more accurate in
the vertical direction. And I found that in fact the SuperDomes usually gave
me a tighter group than the
SuperPoints. Although the difference was not
large, at 40-50 yards, being an inch off is often the difference between a
hit and
a miss. However (there’s ALWAYS an "however"), when hunting crows,
I prefer the SuperPoints. Crows are nearly always shot
from the side,
perched in a tree. (Frontal shots are rare because they would inevitably see
you.) Folded crow wings form a stiff,
very effective catcher’s mitt, and I
have shot crows out of trees with .25-caliber rounds, only to have them get
up after a moment
and fly away! The pointed pellet has a better ability to
penetrate this feather trap and effect a clean kill rather than a momentary
knock-out.
What have we learned? From this comparison we see there is no
such thing as a "best pellet." There are only a lot of
variables in
pellet characteristics. You, the shooter, has to decide which pellet
characteristics are the most important
for the task at hand—and then
pick the pellet that best meets those needs. This can be learned by lots of
trial and error;
or it can be more quickly and accurately learned by getting
a chronograph and testing your pellets yourself.
|
| |