I've had them do that with granite grit in a small feeder, had to get rid of it and just start throwing some out with the scratch once in a while.Ok and it's not so much the expense but the Crack like behavior exhibited by the hens when they eat it. Have you experienced anything like that?
No problem like that with the oyster and egg shell feeder.
https://www.backyardchickens.com/gallery/oyster-plastic-jar.7897731/