Rhodes

"looking at weights of the old British Doubles and they seem to be all over the shop"

That's because you are comparing weights of guns from
different eras.

Old guns, pre WW1 tended to be heavier.

ie Look at the Webley & Scott Screw Grip or PHV1
- and other doubles.

Up to a certain point, most had full length ribs.
After that, they seemed to go to Qtr ribs.

On weight, a heavier gun that is balanced is
better than a light gun that is not balanced
or is barrel heavy.

"600NE..................16 to 18 lbs..................14 1/2 to 15 1/2 lbs
577NE..................12 1/2 to 14 lbs..............11 1/2 lbs"

Too light for me.