With the tremendous
stresses placed on them, cases tend to stretch or lengthen during
firing, and again in the resizing process. Unless this stretching
is held to within the chambers dimensions, the case neck may
reach a point where it is being jammed tightly between the chamber
walls and the bullet. This can raise pressures to a dangerous level,
giving rise to a hazardous situation. In addition to the safety
issue, crimps are strongly influenced by case length. If cases vary
in length, some will be given a tighter crimp than others. This,
in turn, will have an adverse effect on ignition, accuracy, and
velocity. By simply keeping your cases trimmed to a particular length,
all these potential pitfalls can be avoided.
In the reloading
data section of this manual, there are two lengths listed for each
case. The dimensions listed beside the case drawing is the maximum
length. The other dimension, listed in the Test Components heading,
is the Trim-to length. Normally, this is approximately .010" shorter
than the maximum length for rifle cases. In some pistol or straight-wall
cases, this will be only .005" shorter than the maximum length.
When trimming a batch of cases, set your trimmer (if it is adjustable)
to the listed trim-to length.
There are several
different types of trimmers on the market, running in complexity
and price from simple trim dies to motorized trimmers like the Gracey
and Dillon models. There are advantages and disadvantages to each
of the different styles, so well discuss each in turn.
the most basic end of the scale, we have trim dies. Trim dies are
little more than a sizing die, which has been cut off flush with
the case mouth when the case is at the top of the ram stroke. Any
part of the case mouth that extends past the top of the trim die
is removed with a few strokes of a file. The top surface of the
die is surface hardened, so the file cannot damage the die. After
trimming, the case mouth will need to be chamfered and deburred
before the case can be loaded. In their favor, trim dies are inexpensive
and easy to use.
trim die in use. Any portion of the case mouth extending above
the die is removed with the file, bringing it back to its
for only one specific cartridge, they lack the versatility of the
lathe type trimmers. For handloaders dealing with only one or two
cartridges and doing a relatively small amount of shooting, trim
dies may be the easiest and most economical method for keeping cases
at minimum length. Based on a sizing die, they do have certain disadvantages.
Naturally, they are only available for the more popular standard
cartridges, and a custom wildcat would require a specially made
trim die. Headspace cannot be adjusted without changing the case
length, which defeats the purpose of the die. In large chambers,
this may also mean working the brass more than would normally be
desirable. If any of these problems arise with your particular rifle,
one of the other types of trimmers may be called for.
lathe type trimmers are probably the most commonly seen case trimmers
in use today. As the name implies, these trimmers resemble a small
lathe. With the case head held firmly in place by a collet, and
the mouth centered on the mandrel, the case is fed into a cutter.
The trimmers can be adjusted exactly to a specified length, and
locked to trim all subsequent cases to this same length. By simply
changing the collet and mandrel, and readjusting the stops to control
trim length, these units can be used to trim virtually any case.
Unlike the trim die, there is no chance for headspace to be affected.
When using any type of adjustable trimmer, stop occasionally and
confirm that the trim length has not changed.
manually operated lathe-type trimmer is still the most common
trim tool in use today.
type trimmers are available from most manufacturers of reloading
equipment, in both manual and motorized versions. An additional
benefit specific to these trimmers is that they often serve as the
base for a variety of other tools used in case preparation work.
The trimmers marketed by Forster and L.E. Wilson are good examples.
With the addition of a few accessories, this type of trimmer can
clean primer pockets, inside neck ream, outside neck turn, and square
case heads. For the handloader dealing with a wide variety of cartridges,
the lathe type trimmer will likely be the most versatile and cost
last category would include high volume motorized units such as
those marketed by Doyle Gracey, or the Dillon Rapid Trim. These
differ in operation, but both are intended for trimming large numbers
of cases in a short period of time. The Dillon unit uses a sizing
die, similar to the trim dies discussed earlier. Instead of a file,
the case is trimmed by a carbide cutter driven by an electric motor
mounted above the die. Unlike the file-type trim dies, headspace
and trim length can be adjusted independently in the Dillon trimmer.
Trimming different cartridges requires different dies. Again, these
are limited to the most popular standard calibers. On the other
hand, the Gracey trimmer uses no dies at all. With the cutter being
driven by an electric motor, cases are hand fed into the trimmer,
much in the same manner that pencils are fed into a pencil sharpener.
A shell holder (not to be confused with the shell holders used on
reloading presses) provides a ledge on which the case shoulder stops,
limiting its entry into the trimmer and controlling the trim length.
Headspace is unaffected, and the case is not sized in this operation.
motorized trimmer makes it easy to trim large numbers of cases
in a hurry. The model shown is a Dillon Rapid Trim 1200B.
of these units offer an extremely fast method of case trimming,
with production rates of 500-1000 cases an hour. Before purchasing
a trimmer, take a look at some of the different options available
and decide which one best fits your needs. Case trimming is normally
one of the more tedious steps in the reloading process, but it must
be done. Careful selection of the tools used can make this essential
operation much more efficient and cost effective.
and Deburring Tools
are trimmed, a sharp edge around the case mouth will be formed.
This edge must be removed to reduce shaving of the bullet
during seating. This is accomplished by cutting a slight bevel on
both the inside and outside of the case mouth. Most reloading tool
manufacturers make special cutters for this operation. Known as
deburring tools, these small hand held cutters will quickly and
efficiently remove the sharp edges left by the trimming operation.
In practice, the cutting edges of the deburring tool are placed
against the case mouth, and the case is deburred with a quick twist.
There are mounted units available as well, both manual and motorized.
The mounted units are a big help in reducing hand fatigue when a
large number of cases must be done, but in general, deburring is
a quick and easy operation.
not absolutely essential, a case tumbler or polisher will help in
producing good looking reloaded ammunition. There are several tangible
benefits to polishing your cases beyond the obvious improvement
in appearance. Case inspection becomes much easier when the brass
has been thoroughly cleaned. The life of the sizing die can be greatly
extended by removing surface grit from the brass that may otherwise
enter the die and scratch the surface of the dies chamber
walls. If only a small number of cases are being processed, they
can easily be wiped off with a cleaning rag. When large lots of
cases are being done, some form of tumbler is the fastest and most
efficient way to handle the task.
are many different models of case tumblers on the market today,
ranging in size from small rock tumblers capable of handling only
fifty or so .38 Special cases at a time, to large vibratory tumblers
capable of cleaning nearly 600 .30-06 cases at once. Today, dry
media tumblers are the most frequently encountered, though there
are some that use liquid cleaning solutions. A few tumblers can
use both. Since the dry media tumblers are by far the most common,
our discussion will center on them.
handloaders tumble their
cases to provide clean, professional looking loaded ammunition.
Most dry tumblers utilize ground nut shells or corn cob, usually
impregnated with a fine jewelers rouge or polishing compound.
In operation, the tumbling motion or vibration causes the cases
to be polished as the media passes over and around them. The time
required to clean a batch of cases will vary, depending on the degree
to which they are tarnished, the aggressiveness of the polishing
compound, and the action of the tumbler itself. This may be as little
as 15-30 minutes, or as long as several hours to achieve the desired
results. There are presently several polishing compounds made specifically
for case cleaning. While it would seem to be a logical choice, do
not use Brasso or any other type of brass cleaning solutions that
contain ammonia. Strong concentrations of ammonia will chemically
attack the case and weaken it, leading to a potentially dangerous
situation. With any make of tumbler, follow the manufacturers
instructions for best results.
media separator such as
this one from Dillon Precision,
makes separating polishing media from cases fast and easy.
We recommend tumbling
fired cases before they are resized. We have had good results using
a two phase polishing process, tumbling cases thoroughly before
resizing, and again after resizing. This second tumbling requires
just a few minutes to remove
the resizing lubricant, and is best accomplished with a fine-grained
nut shell media. This second tumbling can, of course, be omitted
and the resizing lube wiped off with a clean rag. If the cases have
been tumbled after being sized, some polishing media may be jammed
into the flash hole. Some medias are worse about this than others
(large grained ground nut shell being particularly bad), but tumbled
cases should always be inspected for this condition before repriming.
If media is found in the flash hole, it can easily be dislodged
with a straightened paper clip or dental pick.
of the method used, handloaders should never tumble loaded ammunition.
Doing so may cause a deterioration of the powders deterrent
coating, or, in extreme cases, may damage the powder itself. Either
situation would alter the burning rate, possibly raising pressures
to dangerous levels.
A shell holder
is a single part or unit of parts that provide a method of securing
a case to the press during reloading operations. In most reloading
presses, the shell holder will be a single, machined piece which
snaps into the ram. An entire range of sizes is available, to cover
all of the various head sizes and configurations. There are also
universal shell holders available, such as those marketed by Quinetics
Corp., which utilize a sectioned collet. Shell holder design is
fairly well standardized among the various reloading tool manufacturers,
and most will interchange from one brand to another without difficulty.
Despite this, we feel that it is generally best to use the same
make of shell holder as the press that its used in. This will
help to reduce the possibility of misalignment, dimensional differences,
or any other potential trouble spots.
There are some
presses that use alternative shell holders, such as the Bonanza
Co-ax press, and the now discontinued RCBS Big Max. Both of these
use a shell holder that is built into the press, and is more or
less universal. The Co-ax press uses a pair of plates that are cut
to conform to the size of most case heads, and is reversible to
accommodate different size cases.
presses present something of a different situation, due to their
complexity and specialized features. Most progressive presses use
a shell plate in lieu of the more conventional shell holders used
by singe stage presses. Because of the tremendous differences in
design between progressive presses, shell plates must be matched
to both the case, and the particular press being used. For example,
when loading .45 ACP cartridges on a Dillon progressive, different
shell plates are required for each of their RL550B, XL650 and RL1050
machines. This situation holds true for all other cartridges as
well. There is no universal interchangeability between shell plates
of different brands of presses.