
I strongly suspect the way the average player weighs these types of cards, people would paradoxically like it LESS if it had 6 ammunition.
Not because it's not better CATEGORICALLY, but because it would be harder to empty the entire clip like people feel like they need to on these things not to "waste" anything. I could absolutely believe a player would take a worse card simply because they felt they could use it "efficiently."
So sell it to yourself this way: if you don't think you're ever going to be able to shoot it five times, mentally change the text to:
Cost 2:
Fight: +2 fist, 1+ damage as many times as you want. At the end of the first turn you use this action, discard it.
It's functionally the same for you. If that card sounds good, this is that card. Don't worry about not emptying it. Definitely don't feel like you need to commit to playing weird cards in a questionable bid to try to empty it completely and mess up your deck. It's cheap. Need to shoot a lot at something in a future turn? This card can do that for you -- you don't need to add more nonsense unless you want to.