If you mean pages with no categories, that's https://guns.fandom.com/wiki/Special:UncategorizedPages
Gettiing to special pages involves mousing over the "..." button up at the top right, then selecting "all shortcuts."
Sojovito wrote: Because there are some of them that have pages but can't be found in the Firearms by Tipe Page nor in it's categories
By right you won't be able to find firearms in "Firearms by Type" because that's not where you'll find them.
At this point there might not be a way to just see all firearms uncategorized.
Well, that's bad.