Outlet with 6 12 gauge wires.

Hey all, trying to go around the house replacing some old outlets. Our house was built in the early 80's and for 2 of the outlets in the living room, 12 gauge wire was run to them. They are also switched so there's two circuits.

I am unsure on what the best way to wire this to a new outlet would be. There are 4 total hot wires, I figured I'd side connect 2 of them and back stab the other 2. However I cannot backstab due to the wires being too big. Any ideas?