Look closer. As the Cimarron website states, the gun will shoot .38 Colt (the modern .38 Colt, which is just a shortened .38 Special) and .38 S&W Special, which is the full name for what most of us just call .38 Special. Most folks shoot .38 Special in them. The frame and cylinder are exactly the same as the '72 Opentiop, with a '51 Navy style barrel (but made out of the same steel as the smokeless guns and with the bore sized for standard .38 ammo).
.38 S&W (without adding the word "Special") is a totally different cartridge, not compatible.