Our experience is just to let chicks eat whatever mama is eating. Layer feed/scrambled eggs/worms/raw milk/ really anything we would feed to older hens.
Never had a problem with any.
You might want to read these studies. In these they cut chicks open to see what the extra calcium does to their internal organs in addition to counting mortality.
Avian Gout
http://en.engormix.com/MA-poultry-i.../avian-gout-causes-treatment-t1246/165-p0.htm
British Study – Calcium and Protein
http://www.2ndchance.info/goutGuoHighProtein+Ca.pdf
These studies are based on the chicks eating nothing but Layer. It’s not the percentage of calcium in some of the feed the chicks eat, it’s the total calcium intake over time. One bite won’t hurt them. It’s eating an excess of calcium over a time period that does the damage. If most of what they eat is forage a few bites of Layer won’t hurt them.
Sometimes the damage is not immediately evident. They may be a little less thrifty than they otherwise would have been. Maybe a year or two later they get stressed and die because their weakened system gave out. You’d never connect that to the extra calcium they ate as chicks.