We don't have small stones, they are the size of a fist or larger here. There is a lip between the cutter bar and the belt tha would keep some rocks out. Also where the two belts drop in the center there is a small dead spot in front of the center belt that takes it to the combine,the dead spot catches some stones before they can get in the combine. Our ground rolls pretty good here. With a 1020 head we had to cut out the draws before starting the rest of the field, now the draper will flex enough to cut straight thru.