You need to seek the services of a qualified appraiser.
My rough estimate would be $950 - $1000. That seems to be what they are going for at gun shows in southern Illinois. If the gun is engraved, that would add to its value. You can purchase a new Red Label 28 gauge for $1150 from Walmart (see their website for details).
Most are valued between 700-950 dollars in the condition that you describe.
Impossible to answer without a DETAILED description of ALL markings, barrel length, choke tubes, sights, condition, box, accessories and papers.
Remove the forend, then the barrel. The serial number will be on the underneith side of the bottom barrel at the point where it hinges with the rear stock. You may need a magnifying glass.
The value of a 940A 410 gauge gun with a bird dog engraved on a side depends on its condition. This gun in excellent condition is valued between 100.00 and 150.00 as of 2014.
You need the services of an appraiser.
You don't mention if it is a handgun or long gun or the caliber/gauge, etc.. Not that I don't want to help, but, checking each of the models on Ruger's website would be time consuming. Ruger's website has extensive serial number data for all its models and you can access them. Also, you can call Ruger and they will be glad to tell you
I think you mean RUGER, NOT luger red lable..........?
Basically impossible to value with just the serial number. condition? finish? engraved?
what is the value of browning sweet 16 shot gun
Unknown.
Main consideration is fitment of the gun to her size. She must be able to hold it correctly and comfortably to handle the recoil. Without proper fitment a 20 gauge can feel like it kicks worse than a 12 guage. My wife shoots a 12 gauge Ruger Red Label with a 26" barrel and loves it, perfect gun for her small frame.