In French we have the word poudrière which basically means a "powder house", although the military world seems to prefer the French equivalent of powder magazine.
In English, poudrière gets translated either to "powder keg" (which I think is a barrel) or to "magazine".
My problem with the latter, besides the fact that it has several meanings (without context you'd never think I mean "a place where powder is kept"), is that it's a bit too generic for a weapon storage building, which prevents me from using it without appending "powder".
Is there a clear single word for such a building or is powder magazine still my best choice?