If you planned the meeting with the enemy in Paris you might bring a musket, but you wouldn't carry one normally. I know lots of gun advocates and none of them carry a long gun with them except when they are planning on using it - they carry a small pistol for emergencies, but not the long gun. (they might keep the long gun in the truck, but not on their person). If I was planning on shooting someone in Paris I'd want the more accurate long gun (assuming I could get it to where I need it), but I'm not going to carry it when I'm "our for coffee" and happen to see my enemy.

The novel is more about politics. There are very few scenes where I'd expect a modern solider of any nation to have their gun with them either. (though a few scenes where I would expect one they often don't seem to have them)