Article in The Humane Review 1904 states that, at least in 1883, the Rules were those of Hurlingham. Keep in mind the boundary of the ring (which may have not been constructed until late 1890s) was only 21 yards straight-away from the traps. It also discusses cutting the tail feathers of the pigeons
https://books.google.com/books?id=IycKAAAAIAAJ&pg=PA324&lpg

March 18, 1963 Sports Illustrated "A Border Pigeon Shoot"
https://vault.si.com/vault/1963/03/18/a-border-pigeon-shoot