Annealing

• It is the process of heating and cooling a case, so the brass regains its malleability.
• If brass is not annealed, it will eventually become brittle and break.
• The process extends the life of your cases and saves you money in the long run.
• It also tends to improve the accuracy of some rifles.

You might have noticed it on the neck and shoulder of your rifle cases—a rainbow-like coloration on the brass case. What you are seeing is the result of a process called “annealing,” which is a means of keeping the brass soft. Simply put: The brass is heated to a temperature between 500 and 800 degrees (Fahrenheit) and then quenched to cool rapidly.

The Chosen Metal

Brass was chosen as a material for our cartridge cases for its malleability, strength, and rigidity. It is durable enough to withstand the rigors of life (copper was tried, but it proved to be too soft), yet it is pliable enough to be easily formed and reshaped.

Brass, unlike steel, becomes softer when heated and immediately quenched. Again, in the opposite manner of steel, when brass is repeatedly worked, it will become brittle and crack.

In a perfect world, our cartridge case would be formed to SAAMI specification, and upon firing, the shoulder and neck portion would expand to become a perfect mirror of the chamber, fully sealing the gases in the chamber.

Sometimes, you might find a sooty residue on the neck of your fired cases; this is from brass that has not fully expanded to the chamber diameter. If you see this, odds are the brass is not expanding properly. Annealing can solve the problem.

The Annealing Process
So, how can the reloader anneal their own cases?

The principal idea is to heat the neck and shoulder of the case—but certainly not the body and base. A common method that is inexpensive yet effective, uses a blow torch to heat the cases just enough to get a dull-red glow and then place the cartridges into water.

Automated Annealing Process

View the video below for an example of an automated Annealing machine.