The first thing you need to understand is "Cam over".
To see this in action, mount your shell holder in the
ram of your press with no die in place. Get close and
watch closely. Raise the ram of the press to its highest
point of travel. Move it very slowly at the top of the
stroke and watch it very closely. You will notice that
the ram reaches the top of its travel slightly before
the handle reaches the end of its travel. This is
visible in the action of the ram. It will move up to its
maximum point then retreat very slightly. Very slightly
really means VERY slightly. Usually only .003 to .010.
This is easier to see if you screw in the resizing die
until it lightly touches the top of the shell holder
with the ram all the way down as far as it will go and
at rest. Now move the ram up and down. Before the ram
reaches its maximum - up - travel, the shell holder will
touch the bottom of the sizing die. The press and or the
linkage will spring a little and then the ram will
retreat a little and your shell holder will be back into
easy contact with the bottom of the die. Next screw the
die out about one eighth turn ( approximately 0.009")
Now move the ram up and down there will be a very small
gap when the ram is at the top of its stroke and the gap
will widen a little as the handle continues to its
Most instructions state that you should adjust the die
to touch the shell holder with the press handle at its
maximum travel. This will mean that it will be a few
thousandths below the top of the ram travel and the ram
will cam over when it hits the bottom of the die. This
will insure that the cartridge is pressed into the die
to its maximum depth, thus full length sizing it ( At
least to the maximum amount possible with this die. )
But, what if the die interior is shorter than your
rifle's chamber in the length from the head of the case
to the shoulder of the case. It will set the shoulder
back just a bit. When you fire that case next time, it
will push the shoulder forward. When you reload it next,
it will push that shoulder back. Do you see where this
The photos with this article were created for multiple
1) How to set your full length resizing die to resize
cases to "exactly" fit your rifle chamber ( as exactly
2) How to set your full length resizing die to neck size
3) How to set your full length resizing die to correct
cases that have been fired in a rifle with a longer
headspace measurement than yours and which will not
allow your bolt to close.
A few ideas about adjusting loading dies, sizing or
Reloading dies are normally 7/8" n diameter and
threaded 14 threads per inch. This knowledge makes
accurate adjustments fairly easy.
Since one full turn of the die body turns advances
the die into ( or our of ) the press by 1/14" we can
calculate that that turn moves the die body 1.00/14"
Other amounts can be estimated as follows:
One full turn = .0714"
One fourth turn = 0.0179"
One sixth turn = 0.0119"
One eighth turn = 0.0089"
One twelfth turn = 0.0059"
Turn the width of set screw = .0027"
Eighth turns are easy to estimate if your die body has a
hexagonal locking ring, one sixth turn moves one point
to the location of the next point. If your die has
octagonal locking rings you can get one eight turn in
the same manner.
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A word about step numbers. These steps are the steps I took in this die setting exercising. Your exercise may have more or less steps depending on the condition of your case and on how good you are at guessing how far to thru the die between steps.
This case will be the subject of this
discussion. This is a range pickup. It was
selected because it has a high pressure ring
around the head of the case and because it has
been reloaded before with only neck sizing.
The combination of excess pressure and only
partial sizing suggested that it will quite
likely not fit the chamber of my Remington 700
Expand the photo and notice the following:
1: Vertical striations from the resizing
2: Circular ring around the neck of the
case marking the extent of the neck sizing.
3: High pressure ring. This ring is
actually much brighter "in real life". The
lights make the rest of the case look brighter
and this ring does not shine as much in the
photo as it does when viewed first hand.
When I got it to the shop, a quick test verified
that it would not even nearly fit the chamber of
my Remington 700.
The first step in this process is to blacken the
I normally do this with a black marker but the
marking fluid was so reflective I couldn't get
good photos because of the reflected glare.
In this case, I used mold release. Anything that
will make a very thin coating will do. It
doesn't have to be black but it should be a dark
color that will contrast well with the color of
the underlying brass cartridge case. We will be
looking for the color of the brass shining
through the black coating in the following
A quick measurement of the length of the case
neck tells me it is a little less than 1/4" in
length. To be precise, I can check the loading
manual and determines that it is actually 0.203"
Now run the ram to the top of its stroke and
insert the die until it is touching the shell
Calculate how far to back out the die so it just
barely touches the mouth of the case. The Die
backs out of the press by 71/1000ths of an inch
for each full turn of the die body. If we back
the die out two full turns it will be about .143
higher than before. It should resize only the
first 60 thousandths of the neck.
By calculating the length of the neck in terms
of turns of the die, we get 0.203" / 0.0714 =
2.84 turns of the die will approximately equal
the length of the neck
Now carefully raise the ram to its top position
and resize only the top part of the neck.
Remove the case and inspect your blackening. It
should be mostly removed from the mouth of the
case down to the extent to which the die resized
A quick visual inspection tells you you have
sized less than half the length of the neck so
you can easily go another full turn.
Screw the die into the press one full turn and
This time you have resized more of the neck of
the case and notice that bright ring around the
shoulder of the case. This time you reduced the
shoulder and wiped part of the black off the
body of the case just below the shoulder. In
this case we are still quite away from touching
the shoulder but from our above calculation that
the entire length of the neck is 2.84 turns of
the die, we know we cannot turn it a full turn
this time without impacting the shoulder. At
this time we are not ready to touch the
Turn it another half turn and resize again. This
time note that you are resizing almost the
entire neck of the case. and you have wiped
quite a bit of the blackening off the body of
the case just below the shoulder.
We are resizing the body of the case here
because this case was deliberately chosen
because it was over stretched. Your cases
may not be sizing the body of the case at this
Continue the above steps turning the die in very
slightly, multiple times. Turn it just far
enough that the set screw in the locking rings
moves by an amount equal to its own width. This
will move the die by about 0.002 to 0.003.
You will reach a point where the blacking is
wiped off the shoulder and the brass is shining
In this case, it appears that the neck has not
quite been fully resized but the shoulder has
been touched. ( The shoulder may not have
actually been touched but the shoulder of the
die was within the thickness of the blackening
from touching the shoulder.
Clean the case thoroughly. Try it in your rifle.
If the bolt closes easily, you have a perfectly
NECK SIZED cartridge case. If your intention is
to neck size only, you can stop here.
At this point, this case has been sized the
minimum amount to correctly size the neck and to
apply minimum sizing to the back and not set the
In this case, not surprisingly, the case would
still not chamber in my rifle.
Now I clean the blackening out of the resizing
die with a spray degreaser/cleaner like
Birchwood Casey Gun Scrubber or Berryman's B-12.
Since I have degreased the inside of the die
body, I need to apply a little sizing lube to
the cartridge case. ( very little )
Now I turn the die into the press by one half
the width of the set screw in the lock ring.
This means the locking ring is screwed up until
the set screw moves approximately one half its
diameter. Then the die is turned back in until
the locking ring is snug. This will move the die
by less than 0.002".
(You can also do the same thing by turning
the locking ring up a couple of turns and
locking it in place. Then the die is free to
turn in or out until you are satisfied and then
you can screw the locking ring down and lock it
place with the set screw.)
Yes! This is nit picking but I want the
adjustment to be as precise and exact as I can
possibly make it.
Resize the case with the new die setting and try
it in the rifle again. Continue this until the
bolt closes with no effort. It should feel just
like closing the bolt on an empty chamber.
If it is a little snug, you have one more
adjustment to go. You have now set the shoulder
back to the exact maximum length that will
easily fit your chamber.
With most dies, you will notice that the
die body is very close to contacting the top of
the shell holder. That is because most dies are
made to very accurate and precise tolerances.
If it is not touching the top of the shell
holder, you might be tempted to go ahead and
turn it in until it does touch the shell holder.
This will result in a more "full length"
resizing of the cartridge and will probably size
it closer to factory tolerances than the method
we have described here. If you are reloading for
multiple rifles or multiple people, this is
probably a good thing.
If you are reloading only for your pet target or
hunting rifle and want to achieve maximum case
life and maximum accuracy, don't do it.