The problem with that setup is that you aren’t actually incrementing your charge value… and you aren’t passing that charge value onward to the projectile!
Try something more like this.
Note: I use an Int value incremented by one at a fixed rate of time… so I have a short timeline which loops (at 0.1 in this case) and fires a single event every time it loops. If you want your charge to be more fluid, rather than working in discrete states, you’d instead want to set your Timeline up to have a length equal to the total charge time, and then add a float track that goes from 0 to 100 (or whatever max charge is) over that time. You would just have the Timeline’s main output pin set the charge state directly with that output float, rather than doing the incrementing math that I do, and then its “finish” pin would fire the shot if you wanted auto-fire.
Two schools of thought on the subject, I suppose.