This has been bugging me a bit since I first made a Musket Master, who get Rapid Reload (Muskets).
So just how specific do weapon choice feats have to be? In the case of the Musket Master what all qualifies under "Muskets" plural? The Axe Musket? Double Barrel Musket? The Rifle? If I want to take Rapid Reload on a pistol user, do you take "Pistols" or pick one type like say the Double Barrel Pistol? Or as in the feat do you go by type like "One-handed Firearms"?
Firearms is a unique Weapon Proficiency in that you take it once and get all. Why is it different? If you take Weapon Focus what do you Focus? Just one type of Firearm?
The normal weapons this never really mattered. It was always clearly say "Longsword", and unless another weapon says it counts as a Longsword doesn't apply.
Cool. Important to know cause it changes feat order on some characters. Little point taking Rapid Reload for the Double Barrel at 1 when realistically you can't make it until 2 grand falls in your lap. Also likely means some retraining if any character gets their hands on an Advanced Firearm.