It depends on the type of gun he was talking about. If the gun in question is a revolver, it could mean the chambers in the cylinder are not counterbored. Smith & Wesson used to counterbore most all of their cylinders, as did Ruger on their Super Blackhawk. They stopped doing this because it really isn't necessary, but it did make the gun look so much better without that big gap in between the cylinder and the frame. It also saves money by speeding up the manufacturing process. Bill T.