I would like to add that all of the belted cartridges still do headspace off of the belt and not the shoulder. Even when they are reloaded to a specific rifle the headspace measurement was, still is, and allways will be taken from the belt and not the shoulder of the case. Reloading a cartridge has nothing to do with if the chamber of a given rifle headspaces properly or not. That is the only reason the belt is there and headspace gagues that are machined for belted cartridges are not machined to include the entire case deminsions, just the belt portion and a small amount of the case above the belt so that it can center itself in the chamber. When you order a headspace gague for any of the belted cartridges like a 257 Weatherby, 264 Winchester, 270 Weatherby, 7mm Rem. Mag., 300 winchester mag., 300 H&H, 338 Winchester mag., 8mm mag., 375 H&H, 350 Remington mag., 416 Remington mag., 458 Winchester mag, and many others. They all use the exact same headspace gague even though many may have different case dimensions.