All these .45 ACP pistols were introduced in the early 1990s during S&W’s “gun of the week” period, when a proliferation of models was added to the line with variations in features. The basic mechanical design is similar, with variations in finish, barrel length, sights, type of action, etc. Values will be generally similar but be aware that some of these may be rare and could bring significant premiums — for example very few Model 4556s were produced. A collector market has yet to fully emerge. See Standard Catalog of Smith & Wesson available at GunDigestStore.com for more information. These listings may be expanded in future editions, reader input is invited.