If you are experiencing pressure signs but your chronograph shows that you are substantially under the maximum speed given for the cartridge and bullet weight that you are using, or you have a case head separation, the chances are that the sizer die is not set up correctly for your rifle.

It is quite common for a sizer die to be set up incorrectly for an individual rifle. The manufacturers of die sets give instructions that will work for the set up of their dies, regardless of the specification of your particular rifle. These settings are general settings that will work with any rifle. In effect, if you use these settings, you will make reloaded ammunition that is very similar to factory ammunition and will probably get similar results. Manufacturers of rifles and cartridges follow SAAMI and CIP specifications so that the largest possible cartridge will fit in the smallest possible chamber in a rifle made for a particular cartridge.

Cartridges must conform to a set of dimensions that are given as a maximum size and the tolerance is given as a smaller dimension. Chamber dimensions are given fractionally larger than cartridges but as a minimum size and the tolerance is a larger dimension.

Reloading for an individual rifle allows a much finer setting. It can be customized for a particular rifle and will give accuracy much easier and longer case life. For a production rifle, it replaces the use of a neck sizer die.

Reloading cartridges for a particular rifle requires a bit more time in setting up the sizer die so that the completed cartridges will fit the individual rifle with as little tolerance as possible.


The procedure that follows, allows for the precise set up of the length dimensions of the sizer die.

For checking of the chamber diameter dimensions that are critical to accuracy, see CHECK CASE NECK DIAMETER

For this test you only need a roll of masking tape. 

Many 'solutions' are given for these conditions, ranging from cases that are too old/new, of bad manufacture, crimped too much/too little, loads are too high/low or the phase of the moon is causing bad karma. 

The simple fact is that the sizer die must be set up to the same proximity to the shellholder, as that of the rifle chamber to the head of the bolt.  Not more or less so, exactly so.

9 Times out of 10, if the sizer die is set up correctly for the particular rifle, the 'pressure' symptoms and the case head separations disappear.

Follow these steps, do not leave any step out and complete every stage before moving on to the next.  If anything is skipped or left out, the set up is not done the way it should be and will be a waste of time.


1.  Always use the same shellholder with a particular die set.  The surface 'A' is where the base of the case is and 'B' is where the shellholder sits on the ram of the press.  These dimensions differ from one make to the other and sometimes even within the same make.

2.  Ensure that the cases are trimmed to the correct minimum length that is specified and that the cases are deburred and chamfered.


3.  Bring the ram of the press to the highest position and screw the sizer die down until it lightly touches the shellholder.  Some presses 'cam over' and the ram must be held at the highest position for setting, or tested by moving the lever up and down slightly to give the camming action.


4.  Lube a case and size it.



5.  Clean the case lube off the case thoroughly and then chamber the case and close the bolt. The bolt closes in three stages.

a) The case is pushed forwards until the bolt handle can start turning.

b) The bolt handle rotates and the bolt still moves forwards a small distance as it rides up the cam.

c) The bolt handle rotates and locks in place without the bolt moving forwards at all.

Most bolts work in a similar fashion to the Mauser that is illustrated. Falling blocks,lever actions, doubles and others, employ the same principles but in a different manner.


6.  If the bolt closes easily at b) and c) above, the same as if the chamber is empty, remove the case and add a layer of masking tape to the base of the case and re-try it in the chamber.


7.  Keep adding masking tape to the base of the case and trying it in the chamber until some resistance is felt on the final stage of closing of the bolt, when it locks in place.  Effectively, you are lengthening the case by the thickness of the layers of tape.  The resistance must be felt when the bolt is locked as in c) above.


8.  Now screw the sizer die out by 3 or 4 turns.  

9.  Count how many layers of tape were added to the case head and add the same number of layers to the top of the shellholder.

10.  Put the shellholder into the ram on the press.
11.  Take the ram of the press to the topmost position and screw the sizer die down until it stops firmly on the layers of tape on the shellholder.
Lock the sizer die in the new position and do not re-adjust it again for that particular rifle.  If the die set does not have a screw that locks the ring on the die positively and the locking mechanism consists of friction from an o-ring, sell the die set to someone you do not like and get a proper die set.
The purpose of this procedure is to duplicate, as closely as possible, the distance between the shoulder in the rifle chamber and the bolt face, with the shoulder in the sizer die and the face of the shellholder.
It will be neccessary to shoot through all the cases once, to get the full benefit of the new die setting. Do not readjust the sizer die.  
New cases must be run through the sizer die before further preparation is done on the cases. Do not readjust the sizer die. 
With a properly adjusted sizer die, reloaded cartridges will chamber with some resistance as the bolt locks in place. Do not readjust the sizer die.
If the loaded cartridges start to chamber with greater resistance, it is usually time to trim the cases to length and to anneal the cases.  Do not readjust the sizer die.
If you have any questions about this procedure, please contact me by email, details are on the Contact Us link.


GS Custom Bullets, situated in Port Elizabeth on the East Coast of South Africa, manufactures solid copper, turned, monolithic bullets for hunting and sport shooting. These bullets are used by hunters on several continents, hunting from the smallest of antelope to the largest of dangerous game, using the smooth HP bullet, as well as the more popular HV, FN and SP bullets with the patented drive band concept. GSC bullets are configured for the highest possible ballistic coefficients. SP bullets are mainly used for sport shooting. All GS Custom Bullets are coated.