This is a discussion on What's the difference (revolver question) within the Defensive Carry Guns forums, part of the Defensive Carry Discussions category; What's the difference between a S&W 640 and an S&W 640-1?...
What's the difference between a S&W 640 and an S&W 640-1?
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According to the inter webs: The Dash-number after a S&W model number signifies a modification to the design. In this case, the -1 happened in 1996 when the factory adopted the magnum J-frame.
Apparently it was originally a .38sp but changed around 1996 to a .357mag.
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