What is the difference between the 12 gauge JC Higgins Models 583.17 and 583.20?

Good question. The Blue Book Store Brand Cross Over List says the 583.20 is a High Standard Flight King and 583.17 a High Standard but no model name or number is given. A range of Sears ID numbers will often be the same gun sold in a different year, but in this case there is a .18 and .2 between these models and they are Harrington & Richardson guns. I'd still bet that both these guns are the Flight King. actually 583 17 &583 20 Were made by high standard They are the known as the sears model 10 bolt action repeating shotgun the 583 17 was made in 1949 the 583 20 series was made in 1952 both gun are almost identical the 583 20 has some minor improvements in any case both gun are based on the the H&R 120 and have nothing to do whats so ever with High Standard model 200 flighte king pump shotgun