Without pictures I'm assuming what you have is a Colt 357 manufactured in 1958. They were built on the same frame as the python with the adjustable accro rear sight, but utilized a ramped front sight.

 

A serial number in the 13000 range does suggest a '61 Python. But gunpoor is right, if it is a Model .357, it would put it in the 1958 range. What length barrel does it have? If short it may not appear to be the Python that the serial number suggests. Photos would really help. And Welcome!

 

Welcome to the forum. I indeed expect it is a 1958 Model Three-Fifty-Seven, marked on the barrel simply COLT 357. In fact the 357 was not built on the Python frame, but rather the other way around, the 357 beginning in late 1953 and the Python not until 1955. The Model 357, as it is referred to in short, was the first Colt I frame and somewhat the forerunner of the Python. Many people are not familiar with them. The action is the same as the Python and, although the Python is touted to have special attention given to the fit and tuning, in those days, most all Colt revolvers did.

Here is a 1959 with service hammer and service stocks. Most/many, especially at first, had wide spur hammers and target stocks as shown in the catalog. There are a number of previous threads about the model and more pictures on the forum.

 

Thanks for all the replies. I did some research and was sure it was the Colt 357. But the serial number threw me. Ill get a pic asap. thanks again.

 

Before 1968 there was no requirement to have unique serial numbers on the various models of guns. Thus, several different models had serial 1,2 3 and so on up to 13xxx and beyond. Serial number sequence did not define the model and you had to know what the gun was by other means to date it by serial.