The Model 637 is the one J-frame Airweight in the lineup that lets you cock the hammer. The exposed spur is the entire reason to choose the 637 over its DAO siblings, the 642 and 442 — pulling the hammer back before a deliberate shot drops trigger effort dramatically and lets you use the fixed sights with more precision than a long DA pull allows. That capability matters most for careful shots at extended handgun ranges or when a first shot from concealment needs to count under stress.

The drawback is well documented in snubnose communities: an exposed hammer spur on a pocket or IWB carry gun is a snag risk. On a smooth draw from a jacket pocket, the spur can catch on fabric and slow or redirect the gun. Reviewers and instructors who teach pocket carry consistently advise against pocket-carrying exposed-hammer revolvers without either a hammer shroud or a dedicated holster that covers the spur. For strict pocket carry, the DAO 642 is more practical. For belt or ankle carry where the holster mouth controls the draw entirely, the 637's exposed hammer is a genuine asset.

S&W's J-frame has been in continuous production since 1950, making it the longest-running compact revolver platform in American gun history. The 637 sits in the Bodyguard family branch of that lineage, which introduced the exposed-hammer Airweight concept. At 14.5 oz and 6.31" overall, it's one of the lightest DA/SA revolvers you can buy, and the chrome matte silver finish on both the frame and the 1.88" stainless barrel is as distinctive today as it was when the platform launched.