Welcome to the forum.
To be precise, what you describe is not a Model l10, because that designation was introduced only in 1957. Any similar earlier revolver is a .38 Military & Police, which through the decades came in several model designations.
Yours is probably a .38 M&P Model of 1905, third change, based on the last patent date. It was almost certainly manufactured between 1910 and 1914, but to be precise nobody knows the manufacture date of a single S&W revolver; the factory recorded only the dates on which they were shipped, and they were not always shipped in serial number order. A revolver obviously can't be shipped until it has been manufactured, but sometimes a manufactured gun could languish in inventory for months or even years before being included in a particular order.
Most 1905s are square butt guns, but a small percentage were issued with round butts.
The serial number would be a six-digit number on the butt of the gun and also on the flat underside of the barrel and the rear face of the cylinder. If you found 140xx on the frame when you swing the cylinder out, that's just a process control number the factory used until they got the serial number on all the relevant parts.
I'm looking forward to the photos. We like photos.