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About Pellet Numbers and Pellet Testing
The first thing you need to
know is that competition air guns used in the Olympic disciplines are .177
caliber, which is equal to 177th thousandths of an inch. The metric
equivalent to .177 inches is 4.50 millimeters, therefore the European caliber
designation is 4.5 mm.
Next, you should know that the smallest quantity of match
pellets are typically packaged as 500 pellets and are in containers called tins.
When ten tins are packaged together, they are called a sleeve. A sleeve contains 5,000 pellets and weighs a little more than 6
pounds. Five sleeves packaged together are called a case. A case contains
25,000 pellets and weighs about 32 pounds. Case quantities are normally bought
by schools, clubs, very serious competitors, or those stocking up early for Y3K.
So much for packaging. Next,
you need to know that these .177 caliber or 4.50 mm match pellets are made in different
sizes.
As a way of refining accuracy, and to most perfectly fit an individual
group of pellets to the exact size and characteristics of your gun barrel,
pellets are made in different head sizes. Head sizes start at 4.48 mm and
continue through 4.49, 4.50, 4.51, and 4.52 mm. These sizes are
determined by the various size molds used to create the pellets in the
manufacturing process. But, you ask, isn't one .177 barrel the same size as another .177
barrel? No, not really.
In the barrel manufacturing process, the tolerances are such that the finished size of the lands and grooves
of the rifling, will vary enough from one barrel to another that, while one barrel coming
off of the assembly line might prefer the undersized pellets of 4.48 mm - the
next barrel might be happier with oversized pellets of 4.51 mm.
In a perfect world,
you would discover which head size fits your gun and that would always be the
perfect pellet for your gun - but, we all know we don’t live in a perfect world.
Nonetheless, a myth has arisen in the shooting world saying that a specific
pellet head size is the only information you need to know to obtain maximum accuracy from
a particular target airgun. This myth is derived from a misunderstanding of a small piece of
paper that comes with every target airgun sold, that paper is called a test target.
The airgun manufacturers (Anschutz, Walther, Steyr, FWB, Morini, etc.) include
a test target with each new airgun showing a very small group shot from that
specific airgun. Generally, scribbled beside the group will be some
initials denoting the mfg of the pellet (H & N, RWS, JSB, or Vogel) and a head
size diameter (4.48, 4.9, 4.50, etc). It is a profound misunderstanding of this
test target which causes so much confusion for parents, athletes and coaches.
Unfortunately, the conclusion of proper head size pellets for this particular
airgun is drawn when the new owner opens up his or her
prize new airgun and looks at the owner's manual for guidance and sees the head size written on the test target. The owner immediately thinks that it was selected by the factory as the perfect size pellet for use in
this airgun, somewhat akin to Moses bringing the 10 commandments off of
Mount Sinai. The reality is that head size on a factory test target has about
as much relevance to your final decision on what is the most accurate pellet
for your airgun as Bugs Bunny making that proverbial left turn in Albuquerque.
The test target
is nothing more than a validation from the factory that this particular airgun is capable of
shooting well. The factory IS NOT trying to determine the best pellet for your
gun. In fact, as we will see in a moment, they cannot do this. What the gun
factories want to do is put a sample of various pellets through their guns to
see if they are shooting to their accuracy expectations. The test targets
are shot with a group of five pellets. If they shoot the one group of five pellets
and they get a great looking group, you can bet the next thing that gun will
see is the inside of a packing box, not shooting more five shot groups of
pellets.
Of course they will not always get a great looking group on the first
attempt and often will shoot two or three different five shot groups of
pellets to assess the accuracy of the gun/barrel combination. From that first
two or three groups, they will take the best looking group, scribble down the
manufacter and head size on that test target as a verification that it shot well. Then that
airgun goes
off for final packaging and is shipped to an airgun dealer near you.
If they
shoot the first four groups and none of the groups are as tight as they should
be, then they will shoot another sample of four groups possibly on the opposite
extreme of the pellet size spectrum. Normally, for air rifles, one or more of these
groups will be able to hold an unfired pellet up by skirt, when holding the
target horizontally in the air. As soon as they find a good looking group,
that target will go out with the gun. If none of these attempts show accuracy,
then the gun will go back to have its barrel or regulator checked before coming
back to the test range. The point is, shooting test targets are not attempts by the factory
at defining what shoots well in their barrel, but only that their barrel does
indeed shoot well.
Now then, if this head size
number indicated on your gun’s test target is not the key to the accuracy then
what is? How do you know what pellets you should buy? To really get true
information requires testing your airgun from solid rest with a variety of head sizes and lot numbers.
Lot numbers you say? What are those? Lot numbers
are what are used by manufactures to differentiate between various groups of
pellets having different production characteristics.
In firearms ammunition there are a
lot more variables that can make-up a lot number change. Anything that is
different in the production requires a new lot number. A change from one group
of primers to another, a new box of gun powder, a change in brass, a change in
the roll of lead wire used to make the bullet, a change in the adjustment of
the machine, even a simple tweak will necessitate a new lot number. Often this
means that single machine operating in a normal 8 hour work day could produce 5
or more different lot numbers.
For airgun pellets, there are really only two
variables that create a different lot number, a change in the lead wire or a
change in the machine adjustment. For us at Vogel USA, if everything goes well
and an entire roll of lead wire runs through the machine without any machine
tweaking taking place, then a lot will not be any larger than 12 sleeves, or
approximately 60,000 pellets. If production is stopped in the middle of a roll of wire
and a machine adjustment is made, then that creates a new lot number. If we
stop again and make another machine adjustment, then that creates another new lot
number. So you can see that its possible that lot number could cover only 2 or 3 sleeves of pellets.
To determine what a given pellet's lot number is, we normally only have
to look at the tins, often they are stamped on little stickers on the bottom of
the tin, and they will also be found on the corresponding sleeves and cases. It
is important when choosing lots to be tested, that you determine if the
supplier has a large enough quantity on hand of each lot number you test to
actually supply you with that lot number in the event you choose it as the best
shooting lot in your gun. Often, a supplier will have to hold back those lots being
tested until you make your final purchase, so they won't sell out of the lot you eventually
choose. In fairness to the vendors, you should do your pellet
testing as soon as possible upon receiving the sample lots, so as not to tie up his
inventory of pellets for weeks on end.
Next, we will talk separately
about rifle testing versus pistol testing, since the have two vastly different
requirements.
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Vogel USA, Inc. P.O. Box 85 Monteagle, TN 37356 email: info@vogelusa.com |