As with any firearm, it is not possible to accurately appraise a gun without seeing it. Recommend that you see a local gun dealer for an appraisal.
You can also do your own investigation by looking at other models being sold that are in the same condition as yours. Try the gunbroker.com or a periodical called "The Gun List"
You can also reference the Blue Book of Gun Values which can be purchased on line at various retailers.
Also reference the Standard Catalog of Firearms. Each will vary but the value is probably the average of the two.
100% mint condition book values range from $325.00 to $450.00.