'40 schwinn b-6 fenders rolled edge/non-rolled edge

[35cycleplane]

recently have gone through 4,or 5 sets of 1940 schwinn fenderlight fenders. only year to have the set/rund threaded insert for the fenderlight cover to screw into,pat applied for fenderlight cover,too. thing that's throwing me is,some have rolled edges,some do. what gives? yes,i'm talking about the ends. early/late '40? anyone else have info? thanx,keith