None of the Lefever Arms Co. flyers or posters I have from 1922 up through 1935 mention chamber lengths. The 1938, 1940 and 1941 posters state 12-, 16- and 20-gauge chambered for 2 3/4 inch shells and the .410-bore for 3-inch shells. The Ithaca Gun Co. catalogs list the 20-gauge as being 2 1/2 inch through the 1926 catalog. Beginning with the 1927 Ithaca Gun Co. catalog the 20-gauge is said to be chambered for 2 3/4 inch shells.