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Reloading 101 – Adjusting Reloading Dies

Even once you’ve selected all your preferred reloading equipment and begun using it, perfecting your reloaded ammunition can be surprisingly complex. I’ve had a number of questions, both from EMs and in person at the range, regarding the correct ways to adjust reloading dies.

These are not simple questions, as pretty much every type of press and reloading die is slightly different. In this article I’ll attempt to give some general tips which may at least help with answering some of the questions.

Reloading Presses and Dies – General Comments

Without wishing to state the obvious, the primary source of information as to the correct settings for your press and reloading dies will invariably be the manufacturers manual. It is a good idea to keep a copy of the manual(s) in your reloading area, just in case.

If the reloaded round of ammunition comes out of the final stage (usually crimping) with any form of distortion or deformation to the case, then there is quite probably something wrong with the depth settings of one of the dies. This will often be a seating or crimping issue, but may come from earlier stages in the reloading process. For single stage presses, it should be obvious which stage has caused the problem as each round is individually processed through each stage and can be inspected as it comes out of the press.

For turret and progressive presses, it may not be as obvious. The only way to determine which stage has caused the problem is to remove the round after each stage until the distortion is seen. The problem is then most likely with the die setting of the last processed stage.

Considering the possible variations in reloading systems, I am going to be very generic about the types of dies I am going to address. Some dies do a number of jobs in combination, and are thus quite difficult to discuss, e.g., combination decapping/resizing or seating/crimping dies. Let’s stick to single task dies for simplicity.

Decapping Dies

Decapping dies inevitably have a long thin pin running down the middle of the die (Figure 1), the sole function being to project through the primer hole and thus push the expended primer out of the case. The main risk here is that if the die body is set too low, it may impact the case mouth causing damage to the case. The die body should be adjusted so it does not touch the case, and the decapping pin adjusted so that it barely pushes the primer clear of the case. Some decapping dies (Figure 2) have spring loaded decapping pins and are pretty much self adjusting. Provided the body of the decapping die does not touch the case mouth, these types of decapping dies should only need a rough adjustment to get them in the ball park.

Decapping Dies Photo
Figure 1                                                                                                         Figure 2

The other point worth noting about decapping dies is that with use, the decapping pin may become bent, or work loose in its holder. The pressure exerted by the decapping pin can be quite significant, certainly enough to damage a brass case. If the decapping pin is not correctly aligned with the primer hole, and hits the base of the case instead, there is a very good chance the case will be damaged making further use of the case impossible.

The caution here is, keep an eye on your decapping pin.  Make sure it is straight and tightly held in place. A routine check before each reloading session would be a good idea. The decapping pin often protrudes below the base of the decapping die (Figure 3) and thus can be visually checked for straightness. A simple push with your finger will let you know if it has worked loose.

Complete Decapping Dies
Figure 3

Resizing Dies

The resizing die operates on the outside of the case to return the case to the correct diameter. This needs to be done for the full length of the case. The general procedure is to adjust the die so that it goes down to within about 50 thousandths of an inch of the case rim or groove for rimless cases. I have seen this expressed as “about the thickness of a dime.” For most presses, this will be expressed as a clearance between the bottom of the die and the case holder plate when the die is at its maximum depth. The exact measurement will depend on the thickness of the case holder plate, but an additional 20 thousandths of an inch above the case holder plate should work in most cases. For a die with an 18 TPI thread, this amounts to about a 1/2 turn of the die, i.e., screw the sizing die down till it touches the case holder plate, then back it off by 1/2  a turn. Figure 4 shows this clearance for a .357 S&W Magnum case in a Dillon 650 press.

Sizing Die Adjustment
Figure 4 

Case Belling Dies

Case belling (expanding) should be as little as necessary to keep the new projectile in place during the seating process. Too much belling not only excessively fatigues the case mouth causing premature case splitting, but may also cause the case mouth to catch on the edge of the seating die causing case damage. Figure 5 shows  a .357 case/projectile with too little belling and another with just the right amount of belling of the case mouth required to suit most applications.

Ideal Belling 1
Figure 5

Seating Dies

Seating die depth adjustment depends a great deal on the type of projectile in use, specifically, whether or not the projectile has a crimping groove or cannelure. The other major consideration is Overall Ammunition Length (OAL). As long as the OAL for a particular caliber is not exceeded, the chance of misfeeds, for semi-autos, and cylinder obstruction, for revolvers, should be minimal. Seating a projectile too low may cause excessive pressures in the case during firing, particularly if the load is towards the high end of the maximum powder charge.

Seating depth should be adjusted to make sure the OAL is less than the maximum for the caliber, and place the projectile at the correct depth for the crimping operation.

Crimping Dies

Crimping and seating adjustments are inevitably intertwined, and depend very much on the type of firearm and projectile being used. I covered the issue of crimping in some detail in my previous 3 articles.

The “Cliff notes” version: if you are going to apply a crimp, it should be just sufficient to hold the projectile firmly in place, and not allow the projectile to leave the case during firing until all the powder has been burnt. If the projectile has a crimping groove (cannelure), the crimp should be placed at that point. If there is no crimping groove, the crimp can be located anywhere on the last land (widest part) on the projectile.

The Last Article

This is the last of my planned series of articles on reloading. I hope everyone who followed the series got some useful information. I certainly learnt a lot from my research along the way. Thanks to those of you who provided additional information and constructive feedback/comments.


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