Remington Model 1900s are a simplified, cheaper, version of the Model 1894, built on the same patents -- No. 528,507 and No. 528,508 both granted Oct. 30, 1894. The Model 1900s were all K-Grades, with E added to the designation if the gun had ejectors and D if it had Damascus barrels -- K-, KE-, KD-, or KED-Grades. The K- and KE-Grades had Remington Steel barrels. The Model 1900s had a snap-on/off forearm and their serial numbers were in the 300,000 range, often preceded with a stock letter Q. Remington only used the terms "Model 1894" and "Model 1900" in the parts lists. The the Remington Arms Co. retail catalogue, the guns were all "Remington Hammerless Double Barrel Shotguns" and just differentiated by grade.
Most of the old 12-gauge Remington doubles seem to have been chambered 2 5/8 inch. A few graded guns, ordered by serious shooters, may have been ordered with longer chambers, but not likely an entry-level gun like the KED. This seems kind of odd in retrospect because the Remington Autoloading Gun was chambered for 2 3/4 inch shells from its introduction in 1905.
My Father owned a KED 12-gauge from the 1930s until just after WW-II, when he got a much nicer AE-Grade, and passed the KED on to his younger brother who was returning from WW-II. Both those Damascus barrel Remingtons have digested many cases of Super-X, Nitro Express, and Federal Hi-Powers. They saw lots of service in those great years right after WW-II when Pheasants and Ducks were so thick in the Dakotas. My Father continued to use his AE-Grade 'til he quit hunting at age 80 after the 1988/9 season. His old AE-Grade is in my gun room, still tight and on-face.
The old KED finally was damaged by early steel shot bulging the chokes and breaking the ribs loose when my cousins used it for Geese in Minnesota when no-tox first became manditory.
I don't shoot Damascus guns myself, and I don't recommend anyone else do either.