The Challenger II has an all steel frame and the Challenger III has an alloy frame; I don't know what the alloy is.
I would need to know if we are talking about a browning auto-5 shotgun made in 1904?Please let me know and I will be able to give you a accurate value of your shotgun.Also include if it is a standard model or a grade II,Grade III, etc.
Wood and amount of engraving
That is an 'American Browning' produced by Remington during World War II.
The Stevens Model 520 was built on a Browning patent and so marked. Stevens also built the gun for Sears before World War II under the 'Ranger' tradename, so if you have a slide-action shotgun marked 'Ranger' and 'Browning Patent' then that is what you have.
HRCA grade sheet steel comes in various grades. Firstly, it is 10748/1995, and it comes in grades I, II, and III.
There are three grades of sprains. Grade I sprains. Grade II sprains. Grade III, or third degree, sprains
Your Browning shotgun which was made by Remington was made during the World war II years(1940-1945).During this time the manufacturer of Browning Auto-5 shotguns which was in Belguim was under Nazi German control and were making firearms for the German Army.No exportation was possible.
BROWING AUTO-5 16GAUGE SERIAL NUMBER X17414 MADE IN 1948 (X NUMBERS AFTER WORLD WAR II)
In 90%+ condition about $700 for a 20 gauge and about $550-$600 for a 12 gauge.
Without more specific information on the fininsh and condition; 100-1000 USD
The Buckmark is a newer version of the same design. Challengers came in 3 models or versions (I, II, III), each being made after the former was discontinued. The Challenger III was very very close to the current Buckmark design, with the aluminum frame in common with the Buckmark. Challenger I and II both had steel frames.