Hi. I have a Lefever Nitro Special in 16 gauge that I got from my late grandfather. I don't know much about valuing guns but it looks like it's in good conditions to me (my grandpa always took real good care of his guns). It has a serial number of S 224256. Could someone tell me when this gun was made and approximately how much it's worth? I'll never sell it but want to have a value for insurance purposes.