Yes, she knows how to use some weapons. She’s not perfect with it, but it's enough for self-defense. The gang can't let her be completely helpless with their lifestyle, right?
However, given her low eyesight, she is an extremely ineffective gunslinger, whose everything is based on habit.
On the reference that I did not finish, there is Heather's modest arsenal – rolling block rifle and cattleman revolver. She rarely uses a rifle, only when she is paired with someone (before getting glasses), or when she is in the mood to hunt (if she manages to spot the game before it notice her).
With a revolver, a little more often and with offhand.
Aaaand I don't think we need to talk about goatgirl's relationship with shotguns. The strong recoil shakes her and the weight doesn't really suit her.
Bows also not her thing-