Cartridge Components Part I (Brass)
Every metallic cartridge is made up of four main components, case, primer, powder, and bullet. There are a wide variety of cartridge components available made by many different companies. One of the enjoyable aspects of reloading is the ability to experiment with various component combinations searching for the perfect load. It is important to realize that components are designed for specific calibers and specific uses. A powder that is suitable for handgun cartridges probably won’t provide optimum results when loaded into rifle cartridges. Bullets designed for target shooting typically won’t perform well on game. Understanding the intended use of a particular component will help you choose the right components for a cartridge’s intended purpose.
Cartridge cases or “brass” as they are commonly called are the foundation of a cartridge. The case not only holds all of the components together, but also seals the chamber so that the pressure and gas from the burning powder drives the bullet forward down the barrel. When you think about it, the brass cartridge case is what reloading is all about. Bullets, primer, and powder can only be used once, but a cartridge case can be reloaded over and over again. Reloading wouldn’t exist without the unique ability to save and reuse brass cases.
In general, the cartridge case accounts for about sixty percent of the cost of a round of ammunition. Depending on how you want to calculate cost, after the first firing, brass is either free or becomes progressively less expensive. When you consider that higher quality brass will typically last through more loadings, high quality brass actually costs the same or less than cheaper brass that may not last as long.
Cases are manufactured and designed for one specific cartridge. Some calibers can be loaded in cases formed from brass intended for other calibers, but the vast majority of reloading is done using brass made for the cartridge being loaded. Cases can be obtained either by buying packages of new unfired brass, or by reusing once-fired cases from commercially loaded ammunition. The advantage to buying new brass is that you can obtain larger quantities of brass from the same manufacturing lot. Using cases from the same lot helps to improve consistency which will in turn improve accuracy. At a minimum, only cases with the same head stamp should be used with a particular load. Cases from different manufacturers can have variations in internal capacity or volume due to differences in case wall thickness. Changes in internal case volume will result in variations in chamber pressure, so powder charges should be reduced and reevaluated when changing the brass used with a specific load. If a load is already at or near maximum pressure, loading it into a case with a smaller internal volume could result in an over pressure load. Keeping brass separated by head stamp not only promotes safety, but also helps to improve consistency and accuracy.
Some companies manufacture their brass to tighter tolerances using higher quality raw materials. The benefit of using higher quality brass is that the brass will usually last longer. As brass is worked repeatedly through firing and sizing, it begins to harden and become brittle. Eventually, brass will become so hard that it begins to crack. High quality brass will typically withstand being loaded more times before cracking than brass of lesser quality. Buying new, high quality brass is the best way to develop a load that will provide consistent results for many loadings to come.