The use of a larger diameter contact tip means there is poor, inconsistent electrical contact between the electrode and the inside of the contact tip. The electrode is "slapping" back and forth inside the contact tip only making momentary electrical contact. This translates into inconsistent current through the electrode and results in inconsistent welds.

Try using the proper diameter contact tip. Yes, you might have to change the contact tip more often, but you should see an immediate improvement in your weld quality. The use of 95% argon should give you a nice spray, with little if any spatter, and it should make a nice "whoosh" sound rather than a snap, crackle, pop sound you currently hear.

There's a reason the contact tip is called a "consumable", it needs to be changed, sometime a few times during a shift. The cost of a new contact tip is a lot less than the labor cost of cleaning up the spatter and the improvement in weld quality.

Al