Ok. I'll try to be direct. We have no insider information on the pressure rating of the 042 and early 642, some of which were refinished and stamped 042, being anything other than standard pressure. S&W did not rate the 642 for +P until they introduced the J magnum frame in 1996. So, the 042 and early 642, which shared the same JA frame, were never officially rated for +P. Does that answer your question?
I don't recommend calling or writing S&W on whether the 042 and early 642 are rated for +P. Their CYA answer will be "if it isn't stamped +P on the barrel, don't shoot it." Or, words to that effect. What we have been trying to tell you is irrespective of whether S&W officially rates these revolvers to +P, they were initially designed to shoot it.