20x110 Hispano aluminum and steel case



here is a 20x110 Hispano case made of both steel and aluminum.

The inner part is made of steel with less than a few tenth of mm steel near the cartridge neck. The outer envelope of the case is made of aluminum.

Any idea about that ?

Thanks for any comment,




An interesting case, J-F. Is it French?

The steel insert is of course to stop burn through of the aluminium. When the British were experimenting with light alloy cases in the immediate post WW2 period this was a serious problem. See the attached picture which is from my forthcoming article in the Journal on British experiments.

Now of course, with improved technology alloy cases for cannon ammunition is quite common.



Thanks Tony for your comment.

Bill Woodin identified such case as made by Norma in Sweden. It seems that there are different shapes of the inner steel sleeve.





I have to add here that aluminium cases are only possible because the US developed a “cold” burning propellant.
So working aluminium cases are not a matter of metallurgy, but a matter of powder chemistry.