Sometimes hens just beginning to lay aill make soft shells, sometimes it can be some sort of stress such as heat. Commercial lay rations should have adequate Calcium but the addition of free choice egg shells or crushed oyster shell is fine. Egg shells will get the calcium to their system the fastest. There are some chickens which are just more prone to not utilize the calcium in the rations. My bet is that they will straighten out and be fine.

Well, they are pretty young, and have just started laying. It has also been blazing hot here, like most of the country. Are clam shells OK, or is oyster shell better? How about some kind of calcium supplement, like crushed up rolaids or something like that?

Just take the shells from boiled eggs or wash the shells from eggs cracked for baking and frying and crush them up. If the shells are washed, then the hens won't get the taste for eating eggs and if the shells are crushed they won't identify them as eggs and then start eating the eggs they lay. Mix in with their food ration and that will increase their calcium. There is also supplemental calcium powders you can get at the feed store, but the problem should clear up just with the hens getting a bit older. Wouldn't rolaids be an awfully expensive way to feed hens calcium?

We let our hens free range and haven't had difficulty with soft shells, there might be calcium in bugs for all I know.

Thanks, hotzcatz, that's what I did, and it seems to be clearing up.