A proceeding in revision may be ordered if there is an apparent error or omission in the record or if the record shows improper or inconsistent action by a court-martial with respect to the findings or sentence that can be rectified without material prejudice to the substantial rights of the accused. In no case, however, may a proceeding in revision:
(1) Reconsider a finding of not guilty of any specification or a ruling which amounts to a finding of not guilty;
(2) Reconsider a finding of not guilty of any charge, unless there has been a finding of guilty under a specification laid under that charge, which sufficiently alleges a violation of some section of this code; or
(3) Increase the severity of the sentence unless the sentence prescribed for the offense is mandatory.