My Speer #9 manual shows both using a .358 lead bullets and .357 jacketed. The case diameter for the .38 S&W is shown as .380" where the .38 Special is .379".
The .38 S&W "may" fit into a .38 Special chamber that's not tightly sized, and being a lower-powered round would be safe to shoot--similar to shooting the .38 Spec in a .357 Mag firearm.
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