It's a S&W 44 Hand Ejector 1st Model (Triple Lock New Century 1907-1915) or a S&W 44 Hand Ejector 3rd Model (1925-1949). It's been refinished. The 1st Model was mostly made in .44 Special but few were furnished in .44 S&W russian, .44-40, .45 Colt, .45 S&W special, .450 Eley, .455 Mark II and .44-40. The 3nd Model was also mostly made in .44 Special but a few were made in .44-40 and .45 Colt.
Edit: Like Rigmover said, it's probably a 3rd Model since the 1st Model is a pretty scarce piece.