Don, and others interested, Cyril got back to me about this. Basically, the rules for the weight of pigeon guns were set at individual clubs, major shoots and associations. Mr. Adams described it thusly:
"------in Live Pigeon Trap Shooting on page 245, the notices
reproduced from the 1909 (Interstate)pigeon shooting rules state that in England, the maximum gun weight is eight pounds.
Also, on page 244, the 1900 Grand American Handicap states that eight pounds is the maximum weight of guns to be used in that shoot.
Each Club seems to have its own rules, many of which were in effect from long usage and not formalized in the rules. By 1900 or so, most of them had dropped their restrictions on gun weight.
There never was a minimum weight, so most Pigeon Guns weigh between
seven and nine pounds, depending on the strength and the desires of the shooter."
So, it seems that there was period wherein maximum weight was attempted to be limited to 8 lbs. maximum, but that was pretty much dropped by the last couple decades of pigeon shooting in England. By 1921 it was about over in England anyway, after the institution of The Captive Bird Shooting Act.
Sound like what you remember?
SRH