Thank you so much for your quick reply.... I actually figured it out just now!

The problem was, that the Q-key was assigned to multiple actions (by default!!!) ... this is a very minor bug... The "Controls"-settings menu does not notify me in any way if a multi-key assignment happens...

Hi!

Since I just started playing Factorio, maybe I am doing something wrong... I am playing the first scenario in which I learn to use weapons. I built a sub-machinegun (additionally to the pistol) and also put in some magazines below the sub-machinegun's slot.... the pistol-slot and the magazine ...