You have to clear 2 waves so not that hard though i died like 5-6 times at this part and i agree that reload part is indeed annoying
First wave:
Paul is casting those red explosions so you have to be constanly moving around while clearing the enemies. When you kill the enemies Paul will teleport on top mid circle construction(?) and will do one big explosion starting from left side so you have to run all the way to the other side once the "big red explosion" is over you can shoot him and he will teleport back to original position and wave 2 starts.
Second wave:
Basically the same thing only difference is that once he teleports to top mid after you clear the enemies he will cast 2 or 3 big red explosions starting from either left or right side and you have to avoid them, then couple shots and it's over.
Use time dodge+time walk(? the one you hold LB down) to get away fast from the explosions and it should be easy.