What a find! Fred Lord was a well-known Chicago trapshooter, and was a Professional Trade Representative for Winchester with the great Fred Gilbert. He managed tournaments of the Chicago Trapshooter's Association
https://books.google.com/books?id=EZMwAQAAMAAJ&pg=PA457&lpg https://books.google.com/books?id=6JbaHddByIUC&pg=PA208&lpg 2 7/8", 3" and even 3 1/3" chambers were common with Pigeon guns - not for more shot (limited to 1 1/4 oz.) but more wadding. 1 1/4 oz. 3 1/2 Dr.Eq. was the standard 12g Pigeon load of that era.
In Feb. 1898, C.W. Budd received on consignment a Parker $400 AAH Pigeon Gun SN 87449 with 30” Whitworth barrels F/F and 2 7/8” chambers. LOP was 14” and DAH 2 1/4” with a pistol grip stock and no safety.
Toward the end of 1901, Fred Gilbert received his new Parker DH SN 103649; no dolls head, no ejectors, 32” barrels, ordered by Russell Klein, Gilbert’s brother-in-law
https://digital.la84.org/digital/collection/p17103coll17/id/41367Parker #150583, a CHE with 32" Acme steel barrels, 2 7/8" chambers, no safety, “extra full comb”, and Silvers pad was completed for J.H. Anderson August 6, 1909 with a straight grip, DAC 1 7/16”, DAH 2 1/4” and LOP 15”.
Sporting Life reported guns and loads used by competitors at tournaments and the GAH 1895 until about 1902; I'll see if I can find Fred and his Parker. He did not compete at the 1901 GAH at Live Birds
https://digital.la84.org/digital/collection/p17103coll17/id/42076