(a) If an accused after arraignment makes an irregular pleading, or after a plea of guilty sets up matter inconsistent with the plea, or if it appears that the accused has entered the plea of guilty improvidently or through lack of understanding of its meaning and effect, or if the accused fails or refuses to plead, a plea of not guilty shall be entered in the record, and the court shall proceed as though the accused had pleaded not guilty.
     (b) With respect to any charge or specification to which a plea of guilty has been made by the accused and accepted by the military judge or by a court-martial without a military judge, a finding of guilty of the charge or specification may be entered immediately without vote. This finding shall constitute the finding of the court unless the plea of guilty is withdrawn prior to announcement of the sentence, in which event, the proceedings shall continue as though the accused had pleaded not guilty.