There are many examples of DA/SA semi-automatics, the Little Tom Pistol being the first, followed up by the Walther PPK and Walther P38. Modern examples include weapons such as the Beretta 92, among others. Almost all revolvers that are not specified as single-action models are capable of firing in both double- and single-action mode, for example, the Smith & Wesson Model 27, S&W Model 60, the Colt Police Positive, Colt Python, etc. Early double-action revolvers included the Beaumont–Adams and Tranter black-powder muzzleloaders. There are some revolvers that can only be fired in double-action mode (DAO), but that is almost always due to existing double-action/single-action models being modified so that the hammer cannot be cocked manually, rather than from weapons designed that way from the factory.