My S&W 642-1. On every 642-1 I've seen the left side of the barrel is stamped Smith&Wesson 38 S&W spl +P. I have a S&W 642-1 that's only stamped Smith&Wesson on the left and 38 S&W spl on the right. No +P. I contacted S&W and asked if it was rated for +P and they said no, my 642-1 is not rated for +P. I'm not doubting S&W. I'm just wondering what the difference could be. It's a Airweight like all 642-1 I've seen. Everything looks to be the same. Alloy frame, ss barrel and cylinder. Anybody know. Just curious. Also, dose anybody know how to date a S&W revolver.