Holts measure the barrel thickness and if they are of a thickness not considered safe or in proof the guns are sold as stock action and fore-end only. That is all. The barrels thin over the years and Holts are very particular about selling safe firearms. These ones have just reached the point where the barrels are too thin for Holts to sell. You can by them for parts, have new barrels made or have the barrels re-sleeved.