Colt Model M is a fine pistol and fun to shoot.
However, there is one safety check you want to make, particularly since a dry fire is the only way to get the hammer uncocked for storage.
The firing pin in the Model M is in two parts -- because otherwise it would be too long to insert into the firing pin tunnel. The forward part of the pin has a spring that causes it to retract when the hammer is cocked. If that spring has become fossilized because of age, dry firing can cause the forward firing pin nose to become wedged into the firing pin hole in the breech face, and if this happens, you've converted the pistol into an open bolt auto that fires when the slide is dropped on a chambered round!
Test:
Gun is cleared; nothing in chamber or magazine.
Drop slide into battery.
Pull trigger to dry fire.
Now very slowly retract the slide just enough to view the breech face and inspect to be sure there is no part of the pin showing through the hole.
I've repaired a couple of these. At one time, at least, a replacement front firing pin spring was available for purchase; don't recall if I got them from Numrich or Colt Parts. Replacement requires driving out one solid pin in the slide to remove the firing pins; this solid pin removes from left to right.