The model 10-5 was made from 1962-1977, so your 10-5 would be made sometime between those years. Is the finish gone, or is that a well worn nickel? Are there any gunsmiths around you down there that can check it out to make sure its mechanically sound? If so, and its ok, I don't see why you couldn't shoot any +P in it. 10-5s were ok'd from the factory for +P use.

Thanks for the insight to Mexican gun laws. How many pistols are you allowed to own? I thought I read somewhere once that you were only allowed 1 .380 and 1 .38. Any truth to that?