If an arcane archer took the Firearm Specialist Feat would you allow them to use their arcane archery magic with a firearm? and as a followup @matthewmercer would someone with firearm specialist feat but not tinker's tools proficiency be able to repair a weapon damaged by misfire? @executivegoth as well if you have insights
— Perry Vaughan (@Dr_Overdose) May 11, 2018
Using firearms with that class would be up to your DM. As for the second question, you could still attempt to repair, but lack the proficiency bonus on the rolls to do so. More intricate ones may require someone proficient to repair, depending.
— Matthew Mercer (@matthewmercer) May 11, 2018