I thought, based on the British penny weight concept
A 1 1/8 oz load was intended for a 7lb gun
A 1 1/16oz load was intended for 6lb 7oz gun
A 7/8 oz load was intended for a 5lb 8oz gun
Maybe I have bass ackwards, but I was told that, during the early days of smokeless powder, it was thought that if you shoot a 5 1/2 lb double, 7/8ths oz was the most that should be shot from it...otherwise your subjecting the face of the buttstock to forces that the stockmaker hadn't intended. This obstacle was eventually overcome by many French artisan/gunmakers by utilizing "faux corps de plantines" (which means false body of the sidelocks). What was previously thought of as "false sideplates" were assigned a utilitarian function by French artisans trying to overcome the penny wieght thinking. The sideplates were used to not only encase the head of the boxlock stock, but to add a sizable amount of surface to the area considered to be the face or bearing surfaces of the stock. In the early days of nitro powder, when most makers just moved toward more robust guns, the French sportsmen continued to demand lightweight fast handling doubles. Some of the French doubles of the period are among the lightest ever produced. If your lucky enough to find one thats triple proofed, you've got the zenith of a particular thoroughbred double.
