Store policy or some
local law. I bet it's just policy. Many fllks think there are laws that don't exist. Kind of like the idiots right here in PA that tell others that it's illegal to carry in a bar, open carry, carry in a bank. etc etc.
No ammo returns.... OK, I can see that. Don't want folks switheroo'ing premium ammo for crap.
No ammo after 10PM... That's just plain old ignorance. As if only crooks buy ammo after 10PM

Walmart hires some of the biggest assholes ever to walk the earth... and then promotes them to management.