V star 650 master cyl rebuild

Rebuilding my cuz's master cylinder, just got the kit in the mail, can't figure out how to get the rubber seal to the middle of the piston like the stock one I pulled out. Afraid I'm going to damage the seal if I try to stretch it over the metal collar. Is that how you do it? Or is this thing assembled wrong? I'm probably just being tarded, can anyone help?

Found a clymer manual for it, that is the correct way, guess I need to stretch the seal over the metal shoulder.