Almost looks like your trying to weld zinc coated or galvanized material. If your gun bucks with wire contact and keeps bucking, crank up the voltage first. If it helps but still bucks slow down your wire speed. Run your gun 10 degrees before 90, this will help splatter. If you lean your gun like at a 45 the metal wants to fly off the puddle and create splatter. Flux wire will push or pull but for best penetration keep the top of the gun 10 degrees off 90 behind the puddle and push the nozzle towards the direction of the weld. Keep the contact tip as close to the puddle as possible without freezing the wire. If you run Lincoln, ESAB, Pro Star or a namebrand wire you will definately benefit from it. Get some clean metal and practice, you don't want to get hurt.
ps: Old salt has a lot of merit with his opinion of flux core machines, they sux for the most part, my advise, learn to stick weld and then go wire. Welding courses at community colleges start around 350.00 a course and are a lot of fun. :thumbsup: