Whats the normal size of a full crop?

[SilkieCanada]

Is it normal for a silkie chickens crop to become the size of a baseball? It goes away overnight but then gets big as the day goes on the next day. I dont have enough experience to understand whats normal

 

[aggie9296]

My Red Stars get about that big after a day of free ranging. Full of bugs and rocks. As long as it goes down overnight and they are eating and drinking fine, should be normal for them.