it LOOKS like you do NOT need to disassemble it. And fileing on that surface would be a huge mistake.
Instead try to reform the circularity by putting it in a rubber jawed vice and squeezing it on it\'s (now) long diameter. Monitor the gaps on the sides so you don\'t squeeze the inner barrel, and squeeze it one neat the section with the ding, and you should be OK.
I dunno... that sounds so much better than using a file on it.
