When we slaughter free range chickens I never found any screws, nails, glass etc in their gizzards. I found small quartz stones all about the same size. They are choosy what they pick up for grit and our won’t pick up any other type of stone. The only reason I can think of why they would try to eat a screw, glass etc is if the didn’t have grit. Commercial grit I think is granite and I assume our chickens would eat that if they didn’t have the natural quartzwierd question do hens try to eat screws i was trying to fix a latch of a 5 year old coop and the screw fell into the nesting box i spent over an hour trying to find it but couldnt i even used a screw magnet and found nothing it terrifies me hopefully they wont but i post an image of Comet my comet hen to this thread and yes its a very orginal name