To get the precision badge you have to know when to use the gas and when to run away, then like what karnizero said use that tactic and do not attack from the front.
Mortar are quite effective in my thoughts because if they have high accuracy they can blow just about anything up. I've had it once where a panzer popped up then it blows up a few second later by my mortar. How I place the mortars is I make a trench put the mortar in it then build a sandbag to give him extra protection.
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