Given the limited information provided, it could be worth anywhere from a few hundred to multiple thousands. It will depend on EXACTLY what you have and its condition, accessories, box, papers, etc..
The value of a Smith and Wesson 1897 serial 539443 pearl handle nickel plated gun depends on its condition. This gun in excellent condition is valued between 1200.00 and 1400.00 as of 2014.
50-500 usd
Needs an appraisal
$250-$350 depending on condition
the model if the gun is near perfect condition is 500
225 or so
Your smith and Wesson model 15-3 was made from 1967-1976.That said your revolver is valued between 85 dollars for a gun in poor condition up to 400 for a fine example in excellent condition.
Read this http://www.singleactions.com/VADragoons.pdf
100 or so
Impossible to answer without a DETAILED description of ALL markings, barrel length, finish, overall condition, box, papers, accessories.
Yes, it can handle +P loads.
prices for the model 36 varies. I would estimate $450 - $550