Extra primer pickup tubes allowed me to speed up production volume by having primers ready to load when I ran empty. It takes time to fill the pick up tubes. I use to own a bare 550 with no add ons. I was able to load about 300 rds per hour. I was slow because I was careful. At that time I practiced shooting 1 hour for each hour of loading. I don't shoot at that rate anymore so I just buy ammo now.