Could it have been the Herrgottskanoniere
Artillerymen reminding everybody that thursday was a catholic feast called Fronleicham by shooting multiple times, up to twelve shots per go. However, they're troops from Luzern so not sure how well they can be heard in Zug if at all.
Wednesday 8pm (12 shots), thursday 7am(12 shots), 9am (? shots), 09:20 (2 shots) 09:45 (? shots), about 10am (1 shot), shortly after 10am (1 shot), and finally a bit before 11am (3 shots). This is
their schedule (in German).