The Lefever Nitro Special was made by a division of Ithaca between 1921 and 1948. In excellent (virtually new) condition a single-trigger gun might bring anywhere from $600 to $800, depending on model, and about half that in average condition. This is a fairly low price for excellent-condition American doubles, indicating it’s not hard sought by collectors. Though I can’t tell you exactly when it was made, the high serial number indicates later manufacture, so it should be safe to use with any modern 16-gauge ammunition.