At the frame's opposite end, the Model 500 also employs a new method of barrel attachment. On all other steel-frame/steel-barrel S&W revolvers, the barrel is threaded directly into the frame with a "crush-fit" interface that is forcefully tightened into proper index and requires substantial minimum barrel diameter and frame enclosure material. By contrast, the X-Frame design uses a two-part barrel assembly consisting of in internal rifled barrel tube, and a separate enclosing barrel shroud. In assembly, the shroud is first placed over the index tabs on the front of the frame, and then the barrel tube is inserted and threaded into the frame with an enlarged ring around its muzzle bringing the shroud tightly against the frame as it torques down.
The system is superficially similar to the well-known interchangeable-barrel Dan Wesson system, but unlike a Dan Wesson barrel it is a permanent installation with a hard-fitted, nonadjustable barrel-cylinder gap. Like the Dan Wesson system, however, the result is that the actual barrel with the rifled bore is supported at both ends, not just at the rear, which enhances accuracy. And, most important of all, the barrel portion that is threaded through the frame at the critical location of the forcing cone, which must absorb all the punishing impact of the bullet as it leaps from the face of the cylinder, is a nonstressed interface. This is a real benefit to the gun's longevity, considering the intensely high impact energy of the .500 Smith & Wesson Magnum cartridge.
