A 3rd Model Target would bring more than a 4th Model due to the basic rule of age and scarcity: there are far fewer of them so they sell for more.

This is a really nice gun but I hope you didn't pay the price for a 3rd Model Target as that would be substantially higher than what this gun would probably bring. If the seller represented it as a 3rd you might be able to return it if you feel you paid too much.