Reloading Equipment II (Dies)

Dies are truly the key to the whole reloading process. Dies are essential for resizing fired cases to the proper dimensions to fit into the chamber of a firearm as well as seating a new bullet into the mouth of the case. There are a variety of dies available for performing various steps of the reloading process. Some dies perform multiple operations at once while others only perform one specific operation at a time.

Full Length die with Decapping/Expander Button assembly removed.

Full Length Sizing Die

The main purpose of a full length sizing die is to return a fired case back to the specified dimensions for the cartridge. The Sporting Arms and Ammunition Manufacturers’ Institute or SAAMI establishes industry standards for cartridge and firearm chamber dimensions. For a case to chamber easily in a firearm, its outside dimensions must be slightly smaller than the internal dimensions of the chamber. When a cartridge is fired, the brass case expands outward against the walls of the chamber. Brass has a unique ability to spring back to the shape it had before being expanded, but it doesn’t quite spring back all the way to its original dimensions. To return the case to the proper dimensions for trouble-free insertion and extraction, a full length sizing die is used to reshape the entire body and neck of the case.

A full length die will also contain the decapping rod and the sizing button. The decapping rod presses the spent primer out of the primer pocket by means of a small pin which extends down through the flash hole. The neck expander or sizing button expands the neck of the case back to the proper dimensions for gripping the bullet.

Small Base Die

A small base die is basically an extra tight, full length sizing die. A small base die will size brass down to the minimum SAAMI specification for that cartridge. Small base dies are typically used to size brass that will be fired in semi-automatic, pump, or lever-action rifles. Small base dies insure that brass is sized properly for reliable chambering and extraction in semi-automatic rifles. Reloaders who are experiencing poor functioning in their semi-automatic rifles with reloads may experience better performance through the use of a small base die. Small base dies are typically only available in calibers commonly chambered in semi-auto rifles.

Bullet Seating Die

The bullet seating die seats the bullet into the neck of the case and if desired, will also crimp the case mouth around the bullet. The bullet seating die is adjustable so that the seating depth of the bullet within the case can be varied. This is how changes to the overall length of the cartridge can be made.

The crimp is typically unnecessary for most bottleneck rifle cartridge reloading. Crimps are used on handgun cartridges and cartridges intended for use in semi-automatic or tubular magazine fed rifles. A crimp may also be applied to cartridges which produce heavy recoil to prevent bullet shift.

Neck Sizing Die

A neck sizing die is designed to only size the neck of the case. If a particular piece of brass is only going to be fired in one rifle, it need not be full length resized after every firing. Unnecessarily sizing brass will overwork it and contribute to shortened case life. Many shooters also believe that neck sizing only, produces more accurate ammunition. The drawback to using neck sizing only, is that after cases have been fired several times, they will be difficult or impossible to chamber as the body will have expanded too much to fit back into the chamber of your rifle. Like the full length die, the neck die also contains a decapping rod and neck expander.

Bushing Dies

A very specialized type of sizing die is a bushing die. Bushing dies use interchangeable bushing inserts to very precisely control the amount of sizing performed on the neck of a case. With traditional dies, there is no way to adjust the amount of sizing performed on the neck to account for varying brass thickness. With bushing dies, the neck sizing operation is performed by interchangeable bushings that come in a range of sizes. With these bushings, a reloader can closely adjust the amount of sizing performed on the neck of the case. Minimal neck sizing helps to preserve concentricity and case life while also providing greater control over neck tension. This promotes consistency which is a necessary part of accuracy. For most reloaders, this level of precision is unnecessary, but for those involved in long range competition, it is a necessity. Bushing dies are available for either neck or full length sizing.

Carbide Sizing Die

Special dies which feature a titanium carbide sizing ring are available for resizing straight wall rifle and pistol cartridges. In these dies, the resizing of the case is performed by the small carbide ring held within the body of the die. Carbide is much harder, smoother, and generates less friction than steel, so carbide sizing dies can be used without first lubricating the cases. Since most handgun reloading is a high volume affair performed on progressive presses, carbide dies eliminate the need to lubricate all of the cases being loaded. Carbide dies also last longer due to the increased hardness of the carbide. Because of the higher material cost for carbide and the additional machining required, carbide dies typically cost twice the price of a traditional steel die.

Body Die

Body dies are designed to only size the body of a case without touching the neck. Body dies are used in conjunction with neck sizing when a case becomes difficult to chamber. When neck sized cases have expanded too much, the body of the case is resized, and the shoulder is “bumped” back to proper length through the use of a body die.

Crimp Die

Some cartridges, particularly revolver cartridges, require the case mouth to be crimped into the cannelure or band of the bullet. The crimp prevents bullets from shifting within the case during recoil. Most bullet seating dies include an integral crimp ring, but crimping the case and seating the bullet in one step can result in bullet deformation when using soft lead pistol bullets. Better results and enhanced accuracy can be achieved by performing bullet seating and crimping in two separate steps. For this reason, separate crimp dies are available which only perform the crimp, and no other process. They are available in both taper and profile crimp styles. A taper crimp is used for cartridges that headspace on the case mouth while a roll crimp is used for rimmed cartridges which headspace on the rim of the case.

Expander Die

When reloading straight wall cases, a separate expander die must be used to expand the mouth of the case so that a bullet may be seated. An expander die does not size the outside of the case at all, but simply expands the case mouth slightly so that a new bullet can be inserted.

Decapping Die

A universal decapping die is designed to remove the spent primers from cases without sizing the case. As the die doesn’t size the case at all, decapping dies are made to accommodate a wide range of case sizes and calibers. Universal decapping dies are used to remove spent primers before the case cleaning process to allow for cleaning of the primer pocket.

Trim Die

A trim die is the simplest tool for case length trimming available. Trim dies are designed to be used in conjunction with a file for trimming excess length from cartridge cases. The top of trim dies is hardened so as not to be cut by the file. To use a trim die, a case is run into the die and any portion of the neck extending above the die is filed off with a standard file. A trim die is exactly the right length so that when cases are filed flush with the top of the die, they will be cut to the appropriate length.

Die sets

Dies are available either individually or sold in sets. Dies are most commonly sold in sets of two or three. The most basic set of dies is a standard full length, two die set for reloading rifle cartridges. A two die set contains a full length sizing die and a bullet seating die. Deluxe three die rifle sets are also available that consist of a full length die, a neck sizing die, and a bullet seating die. Die sets for straight wall cartridges come with three dies, a full length sizing die, expander die, and bullet seating die. The more specialized dies such as body and crimp-only dies are sold individually.

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