If they haven't already worked on it, you might see if they can re-expand the dent back out. That's something akin to sticking a circle plug into the barrel, that then concentrically expands pushing the dent out. Sometimes heat needs to be applied if the dent is big like you described. Being at the end, it might make that process even easier. A barrel might be too tough for wood, but you might be able to take a hardwood dowel that has the right diameter, but plane down the side so that it just fits inside. Then, slowly heat and rotate each way and see if the dent works itself out.
Here's a great video from Midway on their dent removal service: