I suppose filling the pistols with water would make it more difficult to re-charge the pistols but it does seem excessive. Maybe Jenny demanded another verse.

I always thought "hurling" had to do with the process of vomiting. Frank Warner sings the line as "Some takes delight in fishing and the bowling" and Molly cuts out Jenny, who "fired off my pistols, and she loaded them with pepper." Well, that gets you out of the water!