Cap'n Kobold
Hero
The proficiency part of the feat may be wasted, but it does allow a character without martial weapons proficiency to become proficient in Firearms if they are martial weapons for example.I agree. It is also a problem that games with guns should probably award proficiency to people with martial weapon proficiency, but that's not how the game works so far. There also should probably be some active ability in the feat, but I think it works okay as is.
The ignore loading effect is a bit boring, but it does address the main issue that a martial-type character would have with firearms, as with crossbows.