Do I need to get a better gun for 12 gauge super magnums? Or could I just use the one **** 12 gauge I have now?

I am interpreting your ****12 as a single shot top break that C ocks when opened or by outside hammer. Most of them are 3" and they are not for super magnum shells.

Think about this. How would we know when you don't say what frigging gun you have? Do you think we're mind readers? What does it say on the barrel? If it doesn't say 3 1/2 inch shells then you can't use it.

Umm

That's been filed off

Shoot the one you have