Turned Brass Cartridges?


#1

I have seen reference here to numerous cartridge cases being made from turned brass. It was my understanding that the normal brass cartridges were softer and therefore withstood the stresses of pressure, etc better than the turned cases made of harder, brass stock. Case in point, the cartridge on the left is a turned 8mm Nambu which was not successful because it split to readily (as I was told). Whats the real story on turned brass case life/quality?


#2

Chief

Turned cases go back to the beginning of cases themselves but are only as good as the guy who makes them. You have to start with a good, hard alloy because the case head has to be hard to withstand the pressure and it cannot be hardened using heat, like you do with steel. The shoulder and neck, on the other hand, have to be soft and this is done with heat, by annealing. The split case that you showed was the result of not properly annealing the neck. Cartridge brass is hardened by working it which is why you will find factory cases that will split after many firings without being re-annealed. Old cartridges with split necks are the result of improper annealing which set up stresses in the brass.

Cases that are drawn or extruded have to be annealed several times during the process (top half only) otherwise they will split. Military brass, and some of the premium commercial cases such as LAPUA, still have the “color” from the final anneal while most factories will polish out the colors prior to loading.

For years, shooters have experimented with cases made with a steel head and a brass body. The military still does such things even today. Some years ago a shooter developed commercial “steel head” cases which consisted of a turned steel head and a brass upper. They didn’t catch on for several reasons and are somewhat of a collector’s item today.

The photo shows two of the O’Conner Steel Head basic cases on the left and a couple of shooter made ones using the head from WWII '06 steel cases.

Ray


#3

Thanks Ray. Makes sense, even a Torpedoman can understand!


#4

There was a small business in UK for many years called NDFS who turned brass cases for obsolete calibres. I have used them myself but have seen them used a lot by other people. They didn’t split any worse than drawn cases but they were only being used for black powder in the main.

The big problem with turned cases is the amount of waste brass that ends up on the workshop floor. From a solid lump of brass as much as three quarters has to be machined away to produce the finished case. That and the time it takes means its never likely to be commercially viable.