Chico recently started grinding pine cone pieces in his water and wearing his beak down similarly. The tip of his beak now narrows and comes to a point a little unnaturally. In the next couple of weeks I plan on slowly grinding down and shaping the tip of his beak a little at a time with my Dremel. Looks like you can get a more natural shape by doing the same or take him in for a grooming. Our birds would stop if they wear too much off as I would think there beak would get sensitive.
You could also take the perch away if he continues to groom excessively.