When you fire a magnum it is accompanied by the cling of a shell casing dropping. The Magnum is a revolver, it doesn't eject casings while it is firing. While minor it is wrong and should be changed.
While testing I didn't hear it every time. It might be dependent on what kind of terrain you are on (dirt, metal, rock, asphalt, pavement, whatever.
Its easier to hear if you fire so that you don't hear the round impacting.