This thing sucks.
A) You need to be firing at enemies that you've evaded, blue player's aren't very good at evading, basically requiring large resource expense or card dedication (and blue player's don't have many evade options). Besides, evading an opponent is an extra action, you'dd be far better off just throwing another attack at the intended target with a Machete or something.. B) You might also be firing at enemies engaged with your allies. A sub-optimal circumstance because now you risk friendly fire AND, as the blue player, it is your job to keep enemies occupied in the first place! If your clue specialist has to spend all his time babysitting your next intended kill then he wont have time to do his job! C) It costs 4 xp! For just 1 more you'dd have a Lightning Gun! Although it's 2 resources more expensive to play it pay's for the difference with 2 extra attack power on every attack (Hitting a rather nice sweet spot of 9 attack total on both current Blue characters.) Also it doesn't have the circumstantial clause.
This weapon sucks, plain and simple. It should cost 2 or 3 XP and be neutral, that way a non-fighter might consider taking it. Often the fighter will find himself stuck in a flood of enemies that he is tanking on behalf of the team, when the going gets tough however the clue specialist has to come running with a Shrivelling or Strange Solution to untangle the battle. A weapon exactly like Springfield M1903 would be perfect for that specific circumstance, sadly this is NOT that weapon.