Many people, when they hear about annealing brass cartridge case necks, jump to the conclusion it must be something difficult to accomplish. Annealing is easy and straightforward once you understand what it is and the equipment necessary.
You may have observed a dark patina on cartridge case brass at the neck and shoulder area. This patina is more prevalent on military cases than commercial. All new cartridge brass has had the neck annealed. Military brass is polished before annealing, the patina is oxidation. Most commercial brass is polished after annealing resulting in the patina being removed. Annealing case necks is a process to attain correct malleability, which in turn provides optimum ductility. When done correctly, it increases brass life and provides uniform neck to bullet tension increasing accurately.
How Does Annealing Affect Brass?
The annealing process for brass is a heat treatment that changes the metal’s physical properties to induce proper malleability, giving the optimum point between dead soft and brittle hard, producing the proper ductility. By altering the internal structure, annealing makes brass more resistant to cracking by removing work hardening stresses. This treatment is commonly applied to cartridge case brass necks to make the metal more malleable. This results in the brass lasting longer and having consistent neck to bullet tension thereby increasing accuracy.
For those reloading ammunition annealing brass cartridge case necks is a follow-up annealing job as the brass was properly annealed by the manufacturer when made. They take great care in examining samples of lots to ensure proper temper (degree of hardness) is correct in each area on the brass. For instance, the head of the case is left relatively hard, this is in order to have more strength in this area to prevent a blowout, this area of the case should never be expanded when fired. If the head of the case is expanded even .0001” it has been subject to excessive pressure, the load was TOO HOT! The case neck is annealed to the correct temper.
Now you shoot the cartridge and then reload it. The neck was expanded when fired. When reloaded the neck is reduced in diameter by resizing in order to hold the new bullet. It is expanded slightly and next a new bullet is seated. Thus, the case neck is moved 3 to 4 times in each cycle. This work hardens the case neck and if not annealed after about 5 to 7 firings brass will start to fail with cracked necks. To prevent the cracking and save your brass neck annealing is the solution.
How Is Cartridge Case Brass Neck Annealing Done?
Traditionally, brass was annealed by hand in a very haphazard method, but modern technologies has made this process considerably more efficient and safer. Here is a look at some of the devices used in contemporary brass annealing:
Electric Induction Annealing Machines
These use an electric induction coil to heat the brass. Electrical induction annealing machines are much more expensive than propane gas flame models. Some makers offer a lab texting service to see if annealing was done properly. If a new batch of cases is purchased or the necks turned then you need to send in more cases for testing.
Propane Gas Flame Annealing Machines
These use common propane torches (normally one or two) with the case neck introduced into the flame or flames for only a few seconds. The neck is quickly heated to 750°F. and allowed to air cool. This returns the case neck to the proper temper.
Conclusion
The process of annealing brass can be of tremendous benefit, as it can extend the life of your brass and increases accuracy. However, if annealing is done incorrectly, you don’t receive the benefits.
Are you ready to start annealing the necks of your cartridge brass cases and searching for a brass cartridge case annealer? Look no further because Enterprise Services LLC is here to offer you the Anneal-Rite, an efficient, accurate, and reasonable machine. It’s durable and anneals cartridge brass necks at the precise temperature of exactly 750°F. Demonstration video can be seen at www.cartridgeanneal.com shop now!
