Yup, from the photos of your cases, I would say they are low pressure and wouldn't worry about the primers backing out. My guess is if you'd bump up your loads in half-grain increments, you'd gradually see those primers stay in their pockets. If you're happy with that loads performance, I say fire away. The loads for my Metford all look like that, and its only a good load for 50 yards, but its cheap and fun.