I don't call them sloppy joe's but barbecue (might be a PA Dutch thin), and I don't like the prepared sloppy joe sauce in a can.
I brown the ground beef and add ketchup, mustard and brown sugar. We make it according to taste, but if I measured it would be 2lbs. ground beef, about 1 cup ketchup, about 2 tbsp. mustard, about 1/4 cup brown sugar. Sometimes I add chopped onion and I also like to mix in red hamburger relish. YUM! Best served on potato rolls (Martin's).