A couple years ago I picked up a brick of Unis Ginex Large Rifle primers at a reasonable price to use in my 308 on my gongs. They are rather tight fitting in both Federal nickel plated and Remington brass cases. They shot well but I don’t like the force required to seat them.
This might be an option for those cases with loose primer pockets.
This batch has many firings and I have lots of brass in this caliber so I don't mind discarding the few and just use the old primers for cast low pressure loads.
I can't enlarge the pic , but what I can see , it does not look like they are leaking gas around the primers . I'd try to tighten them for these low PSI loads . put a little fingernail polish on the head stamp , so you can keep track of them .