Depends greatly on which rolling block, there's to many to specify them all serial/date.
Octagonal barrel could be a plethora of different guns anywhere from a rolling block to a pump. Need to identify what it is first and condition, condition, condition for values.
I have a octagonal barrel .32 caliber Remington Patent date May 3, 1864 - What would it be worth?
Which model, what condition?
Date code on barrel, check Remington Society of America - manufactured date link.
check the date code stamped on the barrel, see the manufactured date link on the Remington Society of America.
1925, check the date code stamped on the barrel. Remington Society of America, Manufactured Date link has the details.
Hexagon barrel what? Model? pump, rolling block, ?? Condition?
The Remington Model 721 in .300 H&H was manufactured in 1948 with a 24" or 26" barrel.
Frank de Haas in Single Shot Rifles and Actions shows the dates of manufacture for the #4 model Remington rolling block as 1890 to 1933. The first type being the rigid frame with screw in barrel. Konrad Schreier indicates the lever takedown type was introduced about 1900 made through 1910 when Remington changed to the thumb screw style takedown system. The last type was manufactured with a round barrel as opposed to the former tapered octagon barrels. The earliest #4s do not have alfa designations as part of the serial number. For photo examples of these types see www.rollingblockparts.com. Due to Remington's incomplete or nonexistant records the exact date of your rifle manufacture may never be known.
See Related Links below