I have seen all the BBBY stress builds and thought about this:

B Wing

E2 Title

Tactician

Flechette Cannon

The question is, what stress is placed first at range 2? If it is the cannon then both would be applied, if it is the crew members, then just the crew's would be applied (only at range 2).

The stress from Flechette Cannon is applied when you resolve the damage - so it happens as part of the attack sequence.

Tactician states:

After you perform an attack against a ship inside your firing arc at Range 2, that ship receives 1 stress token.

Flechette Cannon, then Tactician. So, 2 stress for the defender.