Nephros,
Chart sorting by first name is an idiosyncrasy of AC which makes no sense to me. Bert's suggestion is the only way that I know of to avoid that. Since you (and I) save charts with Ctrl-S, you don't have the naming option. The only other choice is to save it to yourself by hitting "forward chart", then selecting yourself, then renaming the message as Bert suggests. If that is worth the effort, then go that route.
Do keep in mind that you can first filter your box to only show the charts, and THEN sort them by name or date. That is usually enough for me to find what I need pretty quickly.
