Your looking at an old reloader. I have one of the 600 jr reloaders from the 60's. The old charge bars were set up to use Red Dot and other powders of the time.
You can simply buy the new modern charge bars from Mec or a supplier and it will fit right in the old machine. Mec even sells replacement parts for the old 600jr. I still use mine.
Charge bar #'s are the 302 sreies for the single stage Mecs. 30278 for 7\8oz, 302100 for 1oz and 302118 for 1 1\8oz of shot.
If I'm not mistaken, the old "O" bar was 3 drams of Red Dot and 1 1\8 oz of shot.
NRA member, DCF&S member, PAFOA member