If you’ve delved into reloading research, you’ve likely encountered the term “annealing.” Annealing is the scientific process of softening metal. With repeated use, the neck of a rifle cartridge becomes hardened and brittle, increasing the risk of failure during loading or shooting. Annealing addresses this issue by restoring the neck to its original hardness as when it was initially manufactured.

Manufacturing

While annealing can be performed during the reloading process, it is actually carried out multiple times during case manufacturing, particularly during the formation of the neck and shoulder. However, commercial ammunition rarely shows visible signs of the annealing process, as manufacturers meticulously polish and buff each round to conceal any traces.

How is brass hardened?

We all know that metal needs to be hardened to increases its ability to withstand pressure. Most our familiar with the process of hardening metal through the rapid transition of temperature; by heating the metal up and then quickly cooling it in water or oil. This process works for steel and other metals but not brass. Instead, brass has to be word-hardened.

Work-hardened is simply the process of forcibly flattening, stretching, or any other forms of deforming the metal. Because brass is hardened as you forcib

It is common knowledge that metal must be hardened to enhance its resistance to pressure. Many of us are familiar with the technique of rapidly heating metal and then cooling it quickly in water or oil to achieve hardness, a process commonly used for steel and other metals. However, brass does not respond to this method. Instead, brass undergoes a process known as work-hardening.

Work-hardening involves deliberately flattening, stretching, or deforming the metal through external force. As brass is altered in this manner, it becomes hardened, resulting in extremely hard necks and shoulders of the cases after repeated firings.

ly alter its state, after repeated firings, the cases’ neck and shoulder become extremely hard.

Levels of hardness

Many believe that a case has the same dexterity across its entire surface. However, there are at least three different levels of hardness on one round of rifle ammunition. The rim and primer pocket of the case has to be the hardest to ensure there is no deformity that occurs after firing. Because they are so hard, this part of the case does not expand.

The main body of the cartridge is hard enough to withstand the blast of the shot but soft enough to allow it to expand and then retract to be extracted from the chamber. The neck, where the bullet is seated, is the softest and most prone to cracking and failure. This is due to the shaping process of manufacturing.

How to anneal

In the early days of reloading, to properly perform the annealing process required much skill and experience, as well as a little ingenuity, considering many of the processes used had no way of producing uniform brass. Nowadays, it’s as simple as buying an automatic annealing machine that, once properly set up, can spit out hundreds of casings in no time.

Each caliber size has a specific amount of time it must stay “under the flame” for the annealing process to work, but this will be outlined in the manual for your specific machine. Other than that detail, these machines run with little user input.

Downfall of annealing

Annealing isn’t a required step in the reloading process, and is only used on rifle cartridges, as pistol rounds do not have necks. In fact, many reloaders, once the rifle cartridge reaches the point of needing annealing, will simply toss them out and used new brass.

If you are using the annealing process, be prepared to have what is known as fliers in your batch. Fliers are rounds, usually about 1 out of every five annealed rounds, that hit a significant distance away from other rounds in a group. This is due to the inability to anneal each and every round the same.