So what happens if this Pope does come out and say "private firearms ownership is officially against Church doctrine"? What he invokes his "this time what I'm saying is infallible" clause and makes that the official Catholic stance?

Papal teaching cannot introduce utter novelties or contradict Scripture or Tradition. Popes cannot reverse past teachings or make up new doctrines out of whole cloth.

The Catechism (2265) specifically states defense is not only a right but a grave duty and unjust aggressors can be rendered unable to cause harm. Those who legitimately hold authority have the right to use arms to repel aggressors.

How is it you are so misinformed about Catholicism??

So what happens if this Pope does come out and say "private firearms ownership is officially against Church doctrine"? What he invokes his "this time what I'm saying is infallible" clause and makes that the official Catholic stance?

Papal teaching cannot introduce utter novelties or contradict Scripture or Tradition. Popes cannot reverse past teachings or make up new doctrines out of whole cloth.

The Catechism (2265) specifically states defense is not only a right but a grave duty and unjust aggressors can be rendered unable to cause harm. Those who legitimately hold authority have the right to use arms to repel aggressors.

How is it you are so badly informed about Catholicism??