I just watched a video of a gun barrel being forged on /r/artisanvideos and it got me thinking, how were the millions of guns needed for armies all over Europe manufactured on that scale. Was it simply a case of thousand of gunsmiths turning out individual muskets one at a time or did they have industrial processes to help?
It was relatively industrialised - patterns were standardised but the tolerances weren't anything like the engineering tolerances we experience today. During the Revolutionary War, it supply and workmanship got so bad that the calibre could range from 0.66 to 0.71 instead of the prescribed 0.69 calibre bore.
From what I can gleam from secondary sources, the grand arsenals collated all the parts, assembled them or proofed them all before sending them into service. The main arsenals were in Charleville, Saint-Eitenne, Maubeuge and Tulle and Napoleon opened new ones in Mutzig, Versailles, Liege and Turin.
So, to answer your question, yes - they had industrial processes to help.
Source: 'Haut Les Armes!"; Warpons and Ammunition - Swords Around a Thrown by J R Elting (1988), pg 376