The Ace was made only just before/during WWII, and for a time in the '70's or '80's. If it's an early one, it will probably have the Stevens rear sight (some apparently had fixed sights), while a late one will have the Accro sight. Based on that low serial number, I'd bet the gun was made in the 1938-1940 period. Does it have any military markings? Is it blued? Parkerized?