The forearms are exactly the same length, 8 3/4 inch from the end of the forearm iron to the end of the tube that holds the pushbutton.
Width across breechballs -- 28-ga 1 29/32 inch, 20-ga 2 1/32 inch, 16-ga 2 5/32 inch.
Width of frame just ahead of the standing breech -- 28-ga 1 17/32 inch, 20-ga 1 19/32 inch, 16-ga 1 23/32 inch.
Width of forearm iron -- 28-ga 1 17/32 inch, 20-gauge 1 19/32 inch, 16-ga 1 21/32 inch.
My RBL-12 will be a real beast, 32-inch vent rib and beavertail, but sticking with the 4x straight grip stock and double triggers.