That's a huge disparity. If the gun used to be accurate -- I'd check the crown -- perhaps it's been dropped.

Another possibility -- you're used to carrying much bigger and heavier guns -- smaller guns change the whole dynamic of the trigger pull. Big hands swallow them up -- almost as if we have too much hand for the gun -- that leads to unintentional movement of the hand during the trigger-pull. Try a few dry fires. Does the small gun move in your hand (flick up right at the end of the trigger-pull)? If so, slow down the whole trigger-pull and use your weak hand to help steady the strong hand through the pull.

Sometimes after shooting my K-frames I start pushing the trigger of my J-frames to the left (2 or 3 inches at 7 yards). I have seen other guys "heel" the smaller guns -- flicking them up -- during rapid fire they can be off paper high.