Triple Gun
Equipment
Points: 4?
Ability: Choose one of this ships cannons (you may not make a different choice on your next turn). That cannon has 3 shots per shoot action. If that cannon misses, turn this equipment face-down. If that cannon rolls a 1, eliminate the associated mast and remove this equipment from the game.
What’s the intended function of turning it face down?
If it’s meant to shut the effect down as soon as one of the shots misses, a rewording would make that more clear. Something like this: “Each time that cannon hits, it may immediately take an additional shot, up to 3 shots total.”
If it’s meant to allow the shot to be assigned to a different cannon only after a (non-1) miss, you could make it much less complicated by simply removing that “may not make a different choice” restriction entirely. It’s only going to work with a single cannon each shoot action, and you’ll generally want it on your best cannon each time, which isn’t going to change often unless that cannon goes away. That also gets rid of any need to keep track which specific cannon it was assigned to.
3 points seems reasonable for the effect. 4 or 5 would be more appropriate if it didn’t have the 1-roll penalty included.