Hi:
Several years ago I purchased a used S&W Model 638. While cleaning the revolver I removed the rubber grips and observed black streaks on the grip frame. Thinking it was from the grips I attempted to take the rubber streaks off with negative results. I contacted S&W Customer Service and was mailed a box and return form. Several days later I was contacted by S&W and informed that the grip frame was cracked. I was sent a new Model 638 with "THE LOCK"! I later replaced "THE LOCK" with the "PLUG". All in all, I was a "Happy Camper".
Jimmy