Just completed my first hatch (!) and got 24 chicks out of 31 mutt eggs. I think I did pretty well for my first time. Of the 7 that didn't hatch, 5 were very very large buff orp X's, and 2 EE x's. I thought I had read somewhere that both of these types were difficult to hatch. I opened them all up and the very large eggs all had 99% developed chicks- maybe a day away from pipping? The EE's were smaller and less developed. 3 or so of the very large eggs did hatch a few days ago without a problem but for the others I was wondering, are extremely large eggs difficult to hatch?