Here we have brass on the left and aluminum case ammo on right. The choices between aluminum and brass case ammo largely depends upon availability, price and your application. Billions of rounds have been produced with brass cases.
Aluminum cases appeared in the 1980’s. Aluminum case ammo to the best of the authors knowledge has only ever been manufactured for pistol ammo.
The presumed reason for pistol ammo only is chamber pressure, rifle case pressures can go as high as 55,000 PSI. The 9X19mm pistol ammo shown have a rather high pressure of 35,000 PSI. Aluminum case ammo is also available in 9X19mm, .380ACP, .40 S&W, .38 SPL. .45ACP to name a few.
The alloy for cartridge cases is about 70% copper and 30% zinc. Some brass alloys can be around 60% copper, 36% zinc, with a little tin & iron. So Brass alloys vary according to the application.
It is a normal assumption cartridge case alloys will vary somewhat from one manufacturer to the next. Each factory takes due care in every step of production to assure close tolerances and hardness found at various points on their case.
The manufacturers producing aluminum case ammo state it is made from “Aircraft Alloy”. Some common alloys are 1060, 1100, 3003, 5052, 5083, 6061, 6082, & 7075. Pure aluminum is 1000 Series and is far too soft for any structural application, let alone cartridge cases. The strongest aircraft aluminum is 7075T6511 this is used for aircraft structural parts with a yield strength of 72,000 PSI.
Another common aircraft grade is 2024T3511 with a yield strength of 46,000 PSI. So as can be seen “Aircraft Alloy” covers several alloys.
Each manufacturer will undoubtedly choose the alloy which forms best for production and offers sufficient strength.
Brass cases that accept Boxer primers are reloadable having the flash hole in the center of the primer pocket. This makes the case compatible with de-priming dies used for reloading. Boxer primers have the anvil as a part of the primer.
Many reload/fire cycles are possible before the brass either wears out or is lost. Annealing the neck of cases helps extend the brass life which will be addressed a little later. For a good video showing this process go to cartridgeanneal.com.
Research to date reveals aluminum cases are found with Berdan primers. This type primer pocket has two flash holes off-center. Berdan primers cannot be de-primed with the same reloading die as used for Boxer primers.
One method to remove these primers is to pierce them with a sharp pointed tool at an angle and pry them out. Berdan primed cases have the anvil being a permanent part of the primer pocket. The anvil is a raised portion in the center of the primer pocket facing the priming material and directly in line with the firing pin strike. For this reason, it is normally considered Berdan primed cases are shoot and don’t reload.
That said there are some who do reload this ammo but most limit its use to low-pressure loads and only reload it for one or at most two more firings. Very few reloaders will go to the extra labor to reload aluminum cases.
Aluminum Case Ammo: Pros and Cons
Aluminum case ammo has been proven to be reliable and a good choice to obtain/maintain proficient marksmanship. Generally, the more trigger time a person has the more proficient they become. Like all sports you can’t be good unless you practice. The main attraction for aluminum case ammunition is a price.
If the consumer is an occasional shooter burning a box of fifty, two or three times a year the cost savings is going to be very minor currently about $1.00 to $3.00 per 50 rounds. On the other hand, if shooting several cases of ammo per year and not reloading, aluminum cased ammo will add up allowing more bang for the buck.
Even if you are not a volume shooter you may want to lay in a few cases for peace of mind and security, a good idea, just store properly (covered in another post).
The choice between aluminum and brass case ammo should include several pertinent considerations. First is the ammo from a reliable US manufacturer, this is a consideration to assure a reasonable level of quality and safety.
Personal experience has revealed egregious issues with some foreign-made ammo, for this reason, it is personally avoided. An overcharged load can destroy a firearm and/or the user. One firearm manufacturer stated if a certain brand of foreign ammo was used it voided the warranty.
Those reloading ammo can improve the performance of brass cases by annealing the case neck. Brass case neck annealing can increase accuracy and extend case life. Annealing can even be successfully performed on the small 9X19mm Parabellum (Luger) case and is beneficial for cases like .38 Spl., .40 S&W, .44 Spl. & Mag., .45 Colt.
See Anneal-Rite demonstration video at cartridgeanneal.com for brass case neck annealing for cases from 9X19 to .50 BMG, available from Enterprise Services, LLC. It anneals cartridge brass necks at the precise temperature required with guaranteed perfect results.
For questions call (479) 629-5566 Mon-Sat 9am to 9pm.
Tom Wilson ©