I'll just bet ya: Those aren't, 'sizer die rings'. Instead they're incipient case head separation marks. Take a 6" piece of wire coat hanger. Put a small bend in one end sufficient to go inside the cartridge. Use a Dremel Tool to grind a sharp 45 degree angle at the end of the bend. Now you have an inside inspection tool.
Run the sharpened angle up and down the inside of the cartridge case. If you feel any sort of depression, AT ALL, get rid of that case. Sure, you've got to be an absolute saint to never pick up found brass at the range; BUT, I will never understand, 'Why' so many reloaders try to get the very last loading out of a well used cartridge case?
How often you can reload a cartridge case depends on a lot of things. Case stretch is just one of them. In my experience by the time the primer pockets have opened up, the case is already long gone. Depending upon how hot you load, many pistol cases can go for 12 to 15 reloads before the case mouths have to, at least, be cutback and chamfered again. 'Bright rings' on the lower half of the case body? Absolutely no way would I keep that case in service!
In fact, over the years, I've developed the habit of throwing my frequently reloaded pistol cartridge cases away at some point between the 12th and 15th reload; but, then again, I tend to load hot; and I own very expensive pistols - Just ain't worth it to me.