They should be talking about the recoil lugs. When you get the stock the recoil lug inlets will probably be a little loose and the rifle, action and barrel will move back when you shoot it, this is not good. The recoil lug should be bedded so that the lug is tight at the rear with some sort of bedding compound (Acra-glass or Devco Plastic Steel, for example. A few years ago I put a Boyds stock on my Savage Mod. 12; that included installing pillar beds and bedding the action with Devco. The bedding was successful, but I'm not an expert so I'm not going into a long dissertation. If you take the time to read up and understand the process, and do the work carefully it is a job that you can do yourself. There are some good articles with illustration on line about bedding a rifle. They will give you a better explanation than I can. You should read them.