I used different guns. Line cutter for most that stood, and some of the scorpion things. Even the babies. At first, I used the plasma cutter on the pregos, but then I decided at one point to use the line gun, and it went faster. I used the beam gun(I think that's what the machine gun like one is called) when I needed fast action and lots of bullets, and I used that charge beam's secondary fire when dealing with those tiny things that came from the fat necromorphs. Stasis came in handy as well, as well as kenesis. Funny note. Never upgraded my Rig, Stasis, or Kenesis throughout the whole game. Just the guns. The beam gun was one away from maximum, and as I said, Line gun was maxxed out.