As regards optional gun weight, at one point they were offering a lighter than standard weight on their twelve gauge RBLs. I'm not sure if that is still available.
In cruising their web site over time, I have seen considerable weight differences on both their twelve and sixteen gauge RBL's. Denseness of wood, barrel configuration? Not sure why.

The 12 gauge RBL was made in the larger 12 gauge frame and also on the smaller 16 gauge frame.

The lighter RBL 12s were available in the shorter barrel lengths. I did however special order a light 32" 12 gauge which was made on their 16 gauge frame. With a BTFE this gun weighs 7 lbs 12 oz which is not bad for a steel shot capable 32" gun!