Roguish Gunslinger

Firearms are a new and volatile technology, unknown by the vast majority. Those who are able to design or craft these weapons are quickly gaining power and notoriety. However, with power and notoriety, comes unwanted attention. You are that unwanted attention. Why or how you acquired this technology is in the past now, you now own and wield one of the most deadly and dangerous weapons in the lands. But this technology is new to you, and although you have learned a little as you were able to acquire this weapon. It's intricacies still strain you, but as your time with your firearm develops, you will learn more of its secrets. 

Firearm Proficiency

Starting at 3 level, you gain proficiency with firearms. Additionally, if you roll below a firearms misfire score on any attack roll, the firearm has misfired. During a rest, you methodically disassemble the weapon, clean it, and rebuild it, thus fixing the weapon. You still gain all benefits of the rest, but this requires your entire focus for rough an hour, and cannot be done simultaneously alongside keeping watch or any other activity. 

Unknown Technology

Starting at 3 level, you gain a new way to use your sneak attack. The first time any victim is hit by this weapon you can add or sneak attack damage to a hit. This can only happen if the victim has not seen, heard or been hit by any weapon of this kind before. 

Experienced marksmen

At 9 level, you gain proficiency with tinkerer’s tools. As an action, you can attempt a DC15 intelligence check with your tools to fix a misfired weapon. You also gain the ability to reload as a bonus action, and add your proficiency bonus to initiative rolls.

Firearm Artisan

Starting at 13 level, your knowledge of your weapon has grown considerably. Working with your DM, you can attempt to tinker and modify your weapon. These modifications will require parts and a long rest to attach, and it is up to the DM on the modifications effect on the misfire score. An example of this is a suppressor attachment to your firearm. This removes the noise property from the weapon, but increases the misfire score by 1.

Roguish Gunslinger

At 17 level, your mastery of the firearms matches that of its creator. You can attempt to fix a misfired weapon as a bonus action, you score a critical hit on a roll of natural 19-20.  Additionally, you add your sneak attack damage whenever someone is hit by your firearm, even if they have seen or heard of it before.