Just want to add another method that may work a little faster for some (I know it did for me)
You're still going to use level 1-9 in Go Green, Get Lucky, but for the 1st bird, shoot it in an arc that hits the 2nd pot directly, most of the time it will roll through and explode on the 3rd pot, which will then knock the stone structure down onto the 1st pot. About half the time, some gold gets flung over and knocks and destroys the 4th pot as well. Most of the time I destroyed all 4 pots with one bird and at the most two birds. Just made the grinding go faster!