Model 24 is a semi-auto 22.
Remington Model 24 serial no#s were from 00001 to 130,425.Don't know what you mean by long spur and rifle model RW408700?
The Remington Model 721 in .300 H&H was manufactured in 1948 with a 24" or 26" barrel.
This serial number Model 24 was manufactured sometimebetween 1922 and 1935. Approximately 130,420 were made during that time.
1922 - will be date code stamped on the barrel, see related links.
1928, check the date code stamped on the barrel. Remington Society of America, Manufactured Date link has the details.
1930, it will be date codes with month/year stamped on the barrel see related links for information on the Remington Society of America.
1927. You can lookup the month/year by getting the date code off the barrel and looking it up on the Remington Society of America Manufactured Date link.
Remington firearms are not dated from a serial number, but by a 2 or 3 LETTER code stamped on the barrel, left side, about a quarter inch from the receiver. Go to the website for the Remington Collector's Society for a table showing how to determine the month and year made IF the gun has the original barrel.
I don't have the 24's serial number list but all the 24's are date code stamped on the barrel. Check the Remington Society of America to decipher the month/year here: http://remingtonsociety.com/rsa/questions/barrelcodes
model #24
1929 to 1933 The Improved version of the Remington model 6 became available circa 1905, and featured a blue frame in 24 in. barrel. Production continued until 1933. The earlier models had the original case colored frame.