Yes, we do recommend feeding out poultry shell grit to your hens!
We feed out Westons Peak Layer pellets to our laying birds and the soluble calcium levels in this commercial feed are adequate for eggs production with sound shells. However for those birds that are in enclosed runs and do not have access to large areas of free-range we provide shell grit separately. Shell grit has 3 benefits over the soluble limestone they add in the feed.
At Appletons we fill a small pot planter (or an old pottery dish with a hole in it) secured by a wire stake in the ground (so the birds don't knock it over!) with shell grit. Don't forget to line it with some weed mat to contain the grit so it does not all wash out! Available in a 2kg, 5kg and 20kg bulk bag.