I'm not a big fan of curls. In fact, I can count on my back hairs how many reps I've done over my lifetime. And I'm not a sasquatch!
Anyway, I think those that want to pump up their pea shooters like to perform a lot of different exercises. Barbell curls w/ chains are a great way to accommodate the strength curve and get more resistance at the top.
The only thing that I would advise you to do is make sure that when the barbell is at the top, be sure that there are some links of the chains on the floor. This will eliminate the swing of the chain. Perform the reps smoothly and this is not the exercise to perform with a hint of a cheat (i.e. don't perform an underhand hang clean).
Reps? Do it till you bust out of your Under Armor!