The Breakfast Gun goes on whichever side the diner's firing hand is.

Edits below!

After some discussion and reflection, I agree with @Zachariah@lemmy.world that the Breakfast Gun would indeed go on the left, "to show you plan for a peaceful meal."

Furthermore, presentation of Firearms depends on the level of dining:

At a polite table, guests are expected to lay their Meal Arms down holstered, so as not to soil the table linens. Placing a Meal Arm directly on the tablecloth is a sign of disrespect.

At a formal table, a Firearm Napkin will be provided for each diner. This allows diners to display their Meal Arms openly without soiling the linens.

At a "high table," Meal Arms will be provided by the host. These Arms, while fully functional, are adorned with many engravings and flourishes, as a demonstration of the host's status, and the diner's status as a guest at the table.