You should be fine with cases fired in your gun, but I was curious about cases you might have picked up.

As far as lasting longer, case mouths are the weak point and you will probably split/tear them before you run into problems with the bases. I could be wrong on not resizing though. I resize everything, mainly because I want easy loading and extraction of fired cases.

If a loaded round will not drop easily and fully into your chamber, it's out of spec.