I don't think anyone saw this coming!
This is the first entry that I read and thought, "I want to play that."
I could see this class getting about 2 or 3 more archetypes. If it's to be in the same book as the Mystic, that class is allegedly getting 6 subclasses.If you want a real feel for the 3.5 Artificer, particularly for meleeficer, you could still do worse than a slightly rejiggered Forge Cleric with a splash of this class for the tool expertise.
Its not balanced at all because the gunsmith is broken too. Its rogue sneak attack (close analogue) without the need for a distracting ally plus an aoe he can do plus a cr2 pet plus magic plus magic items plus crazy utility. Its broken. The cunning action, evasion, etc doesnt come close to making up the difference for the amount of op that this class gets.
I could see scaling the pet back, mostly because no one seems to really want a Large construct pet and would prefer a small clockwork familiar instead, but I can’t really get behind your other points. Everything I’m seeing puts the artificer a little behind the curve, not way ahead, so I don’t think it needs nerfed almost at all.Again, take that pet, make it a familiar. That cuts down some of the early level brokenness while keeping the late game utility. Reduce the number of magic items to 4 (remove the final tier) and start getting them at five (bunmp them back). Take that damage and dial that crap back. It should not equal a sneak attack. Maybe, maybe it could equal a warlock's eldritch blast (or slightly exceed it on the gun due to bonus action reload needs) The aoes should be tiny (like acid splash tiny or maybe a 10 ft square) and their damage should be at most fire bolt damage). Also, the spell casting shouldnt be its own wierd progression. Too many corner cases is not what 5e is supposed to be about. Consider 1/3 warlock and have it be like the Warlock where you have to choose your spells. That will rein in some of their sillyness.
If the above is done, its still a useful, viable and fun class. It just isnt some kind of ranged juggernaut that makes warlocks and rogues useless.
Its a poor list because in actual play this would outclass a rogue or warlock. A few reactive abilities do not make up for flexible, consistent aoe or single target damage.
Also a ranged rogue also has 1 chance on its damage can pull it off less consistently.
This guy is getting infinite double damage super cantrips with infinite aoes, a robot dinosaur and free magic items.
The numbers dont add up on this class. It gets too much and gives up too little.
Its a poor list because in actual play this would outclass a rogue or warlock. A few reactive abilities do not make up for flexible, consistent aoe or single target damage.
Also a ranged rogue also has 1 chance on its damage can pull it off less consistently.
This guy is getting infinite double damage super cantrips with infinite aoes, a robot dinosaur and free magic items.
The numbers dont add up on this class. It gets too much and gives up too little.