No rocks to speak of.My uncle told me years ago to leave off of door in corn cause vibration was hard on latch.That's what I did for 19 years with the old A2.Tbran said n1,3and5 for corn and beans.(that's basically what the book says also)Soooo that's what I did .My bars ars welded and have extra short bead in center of tooth which kinda mimics standard bar profile.I don't know if that's why 5_8 worked or what.A few broken cobs but not split.I started at 3_4 and was leaving too many kernals on cob. Next 11_16,then 5_8.I'm sure varieties make a difference too.Same n on my 44A.Them 1_2 rounds are $60+ apiece!!I didn't have time to fool with it so I bought them.I bet my machine shop could get 1" 1_2 round stock cheaper,then drilland tap your own holes.