I'd agree with Bam-Bam that, if it is a top break and the serial number is correct, it is probably a .38 Double Action (4th Model). Another top break gun, the Safety Hammerless model, was produced in the 1930's (when his father was an officer), but there was no Safety Hammerless with the serial number that you show.
As mentioned, a picture or two would be enormously helpful, particularly so if you are looking for some estimate of value.