The Remington cases look the same. Are those nickel plated or cupronickle? Those do not look like reloads - those cases are factory fresh.

Since when did Remington use Nickle plated bullets? I have to disagree none of that brass looks remotely factory fresh, look at the 3 still in box, one can see spots and stains and dirt under the rim. Could they be "new" surplus of some kind? Maybe, a picture of the headstamp will tell the tail. Whatever they are a little blow by at the neck is a none issue. Nothing is wrong with the Op's rifle the reloaded ammo brass is just plain wore out.