Once the case
has been inspected and lubricated as necessary, resizing, the first
mechanical operation of the reloading process, is performed. As
we have discussed, when a cartridge is fired the case is forced
outward against the chamber walls, stretching it beyond its original,
unfired dimensions. Before the case can be reused, it must be returned
to dimensions that will allow it to re-enter the chamber and hold
the new bullet. This process is accomplished through the use of
a resizing die. There are a number of different approaches to resizing,
each suited to a particular reloading situation.
is used on some single shot handguns, when the cases are to be reused
in the same firearm in which they were originally fired. As the
name implies, the neck area is the only portion of the case that
is resized. In a properly dimensioned, properly adjusted neck sizing
die, the case body will not even touch the inside walls of the die.
This often results in the reloaded cartridge giving a slight amount
of resistance when it is chambered. This is of little concern for
slow-fire shooting. However, if ease of manipulation is a concern,
it must be considered. We recommend against neck sizing for any
type of hunting application, due to the risk of a tightly chambering
cartridge tying up the gun. Adjusting a neck-sizing die entails
screwing the die body down into the press, until the bottom of the
die is just above the shell holder when the ram is at the top of
its stroke. When neck sizing a fired case, run the case up into
the die, and inspect the neck area for proper sizing. This will
appear as a burnished area stopping just above the shoulder. The
sizing is adjusted by raising or lowering the die body. When neck
sizing, the neck is the only area that needs to be lubricated. This
is best done with a dry lubricant such as graphite, and a case neck
sizing is the most commonly used form of resizing. Full length sizing
dies reduce the neck and body dimensions of a fired case to allow
free and easy chambering. In most instances, full length sizing
will reduce the case dimensions enough to allow it to be used interchangeably
in several different rifles chambered for the same cartridge. Contrary
to popular opinion, full length resizing is commonly used by the
vast majority of competitive shooters, especially in those disciplines
where rapid-fire is involved. It should be clearly understood that
full length sizing does not reduce a fired case to its original,
unfired dimensions. The goal here is to bring the case dimensions
down far enough to allow the reloaded case to be chambered without
of the full length die calls for the die body to be screwed down
in the press until it contacts the shell holder at the top of the
rams stroke. If the ammunition is to be reused in the same
gun the cases were originally fired in, back the die off 1/2 to
3/4 of a turn and size a lightly lubricated case. Wipe the case
dry, and chamber it in the gun. If any resistance is felt, lower
the die body another
1/8 of a turn (or less), and repeat the process with another fired
case. This is repeated until the action will just close without
resistance. When this has been accomplished, set the lock ring to
secure the die in place. This method will ensure that the fired
cases are resized with a minimum amount of headspace. This case
has now been custom fitted to that particular chamber.
This will normally
provide the best case life and accuracy, but does require that the
ammunition only be used in the gun in which it was originally fired.
If the ammunition is to be used in a different gun of the same chambering,
of course!, the sizing die should be adjusted down until it just
contacts the shell holder at the top of the rams stroke.
results in a slightly greater amount of headspace, but will allow
the ammunition to be used in several different guns. Whichever adjustment
style is used, full length sizing is generally the best sizing method
for most shooting situations.
A lubricated .308 Winchester case is about to be resized and
deprimed. Most presses also offer the option of priming at this
will require that fired cases be returned to approximately unfired
dimensions. This is the purpose of the so called small base sizing
die. In essence, this is nothing more than a standard full length
sizing die, which has been reamed to absolute minimum dimensions.
Tight chambers, a lack of camming power, or a combination of these
may require cases to be sized to these smaller dimensions to assure
positive chambering. As we have noted, most conventional full length
sizing dies reduce a cases fired dimensions enough to allow
the case to be easily rechambered, without bringing it down to its
original, unfired dimensions. In some instances, this will not quite
be sufficient to assure positive operation and functioning. This
most often occurs in firearms that lack the camming power of a bolt
action, such as semi-autos, pumps, and lever actions. Sierra has
worked with a large number of these types of firearms that functioned
perfectly well with conventional full length dies, and suggest resorting
to small base dies only if they prove to be necessary. They do work
the brass more, and will usually result in reduced case life.
for a small base sizing die is exactly the same as for a full length
sizing die, but special emphasis should be paid to avoid exceeding
allowable headspace dimensions. Chamber type case gages, such as
those available from L.E. Wilson, or micrometer gages like the RCBS
Precision Case Mic are extremely useful in adjusting small base
resizing is the result of improper die adjustment in the vast majority
of cases. Of all resizing problems, insufficient resizing is the
easiest to identify, since you will not be able to chamber the reloaded
cartridge. In most instances, this can be corrected by readjusting
the sizing die according to the instructions given under the heading
of Full Length Sizing.
included with most die sets suggest screwing the die body down until
it contacts the shell holder, when the ram is at the top of its
stroke. We feel that this is undesirable as it often results in
excessive resizing, which in turn, can result in reduced case life.
While this may be necessary when the ammunition being loaded will
be used in a number of different firearms, we strongly recommend
that resizing dies be adjusted using the first method described
in the Full Length Sizing section whenever possible.
dies have become tremendously popular in the past ten to fifteen
years, and for good reason. As we have already seen, carbide dies
do away with the necessity of lubricating cases prior to the resizing
process. They do require some attention to how they are set up,
to avoid damage to the die, and obtain best results. The often repeated
advice to screw the die body down until it contacts the shell holder,
will give poor results with a carbide die and may even result in
cracking the carbide insert. NEVER adjust the die body down so far
that it will contact the shell holder. Carbide dies for straight-wall
cases are not designed to full-length resize, and are frequently
adjusted to give what amounts to excessive resizing. This often
results in an undesirable bulge slightly above the extractor groove.
Often called the Coke bottle effect, this will cause
the brass to be worked excessively and can lead to reduced case
life. The only portion of the case that needs to be resized is the
area that is expanded by firing. For use in revolvers especially,
the case need only be sized enough to allow the case to chamber
freely again. Often, this may involve sizing only half the length
of the case body and is in effect, neck sizing. If this is enough
to allow the case to be chambered easily, then the die is adjusted
down far enough.
This will avoid
overworking the brass, and will eliminate the so-called Coke-bottle
facet of die adjustment that is seldom mentioned is squaring
the die The industry standard for reloading dies is a 7/8
x14 thread. Virtually all U.S. reloading equipment manufacturers
thread dies and presses for this pitch. This is coarse enough to
allow for fairly rapid die installation and removal in reloading
presses, but is still fine enough to maintain a good degree of precision
and alignment in assembly. Unfortunately, in many instances, there
will still be some misalignment between the ram/shell holder and
the die body.
Carbide dies, such as this Titanium Carbide set from Redding, eliminate
the requirement for lubricating straight-walled cases prior to sizing.
To square your
dies, start by following the adjustment procedures outlined above,
up to the point of locking the die. Rather than merely snugging
the lock ring down against the top of the press and locking it,
the dies are squared by lowering the ram slightly, and placing a
flat machined washer between the die body and the shell holder.
Raise the ram slowly, until the washer is putting light to moderate
pressure on the bottom of the die. This will remove the play from
the threads, while the flat washer helps to hold the die body square
against the shell holder. Maintaining pressure on the die body,
now lower the lock ring, and lock the die firmly in place.
applies to both sizing and seating dies, but should not be used
with either carbide sizing dies or benchrest/competition seating
dies. You will find that dies that have been squared in this manner
will be somewhat difficult to remove from the press. If the lock
ring must be loosened to remove the dies, simply repeat the process
the next time you set up to reload. The time this procedure takes
to perform is minimal, and we feel the results are well worth the
removal of the fired primer) is normally accomplished during the
sizing operation. In most resizing dies, this is accomplished by
a centrally located decapping pin held rigidly in the die body.
In adjusting a sizing die for primer removal, the decapping pin
should be set low enough that it will knock the spent primer completely
free of the primer pocket, but not so deeply that the decapping
rod will contact the web area on the inside of the case. This is
normally accomplished by raising or lowering the decapping rod within
the die body, and locking it in place once the proper level is established.
An important note of caution here: NEVER attempt to remove live
primers, as they can be detonated during the decapping process.