I picked up a nice used 640 no dash. It is chambered in .38spl with the 1-7/8" barrel. I plan on using .38s at the range, but want to know if I can carry 38+Ps and not shoot them unless life depended on it. I know some early 640s had "rated for +P" on the frame and the catalog of S&W, pg 263., says they were rated for +P. But mine does not have any indication of 38+P on it. Serial range BFZ47...., 1991? Does this sound ok to do?