While dm, however, it had no CA (it is in a 1/2" counter form).Only the Russian made BM obr. 37 82mm Mtr (to the best of my knowledge) can change its CA (either by firing or per C3.22) after having established its CA during the assembly process in the same player turn.
That is correct, however one can always change a CA with/for a shot or at the end of the Fire Phase without firing if it still retains the ability to fire. I would imagine the circumstances involving a CA change at the end of a Fire Phase in which it has been assembled would be rare but not incomprehensible.The unusual capability of the Russian 82mm MTR does not involve the CA. It is that it can fire (once) "in the same phase either prior to becoming dm or after reverting to non-dm status."
Only if one prematurely assembled it early in the Fire Phase, then realized later that he wanted to fire it. Should never happen if one handles it correctly.That is correct, however one can always change a CA with/for a shot or at the end of the Fire Phase without firing if it still retains the ability to fire. I would imagine the circumstances involving a CA change at the end of a Fire Phase in which it has been assembled would be rare but not incomprehensible.