I would estimate it was made post WWII. The Sn range for 1943-1947 is 269000-50001. What it's worth depends on if it left the factory the way you describe it. I suggest you get it lettered by Colt. Go to their website for information on how to do this and price. You don't describe it in terms of Good, Very Good, Fine, Excellent or 90 95 percent, etc. Without that, there is no way to give a good estimate of worth, If it letters as factory nickel, ivory grips and engraving, you are looking at a price range of a thousand or so to multiple thousands, depedning on condition, accessories, box, manual. If it is not factory, and was done during the period, you could still be in the high hundreds to a few thousand or so. Again, it will depend on condition, etc.. If it was done say in the last 20-30 years, it will all depend on the condition of the plating, how good a job was done, who did the engraving, who did the ivory, etc.. In that case you would be in the couple of hundred to maybe a thousand or so price range.
Barrel plating usually used for singulated units. Current supplied to the units by means of "fingers"/tangler in the barrel. Rack plating usually used for matrix work piece. Workpiece need to be placed in the rack for plating. Both platings hv similar plating concept, but pysically the plating done differently.
Barrel and rack plating
This was a trade name made for Belknap Hardware, and from the list of makers (Crescent, H&R, Stevens) it's unlikely to be a high quality gun, but I could be wrong. The plating and engraving were probably not factory original. If this is a double barrel, the usual quote is $150-$250, and for a single shot, $35-$75.
Button RIFLING is a technique for making a rifle barrel. The hole is bored, and a very hard carbide button is pulled through the barrel, engraving all of the grooves in one pass.
Can't be answered without a detailed description of all markings, barrel length, accessories, box, papers, condition
100-10000 usd
around 320.00 US
Depends on condition and whether it has the original box and papers.
Impossible to answer without knowing who made it.
Proofhouse.com has sn tables
1950
Impossible to answer without knowing who made it, barrel length, caliber, finish, condition, box, papers, accessories, engraving, etc..