What season and what year? Assuming that's not a typo and it was 223 Remington. 223 has never been legal in Iowa to hunt deer with since the inception of the DNR and gun restrictions for hunting deer. Many years ago now (10+) when a few counties allowed regular shouldered rifles of smaller than 35 cal, it was .243 and larger diameter only in those counties. .223 was even in the DNR book as being strictly illegal to hunt deer with. I'm not a game warden, but sounds like he should read up on the laws better before hunting as Iowa game wardens will gladly claim your rifle, your truck, and your hunting license if they catch you not following their regulations.