I went ahead and took the photo of the butt of this model 2, with the dubious SN of 10, and a pic posted by breakaway500.
Note, as Mike said, the position of the numbers is not right for a 2 digit gun. The "10" is very much indented, so the point where when I duplicate the approx. spacing, a 6 digit SN fits. Note on the breakaway500 butt, there is room for 1 more digit.
The red lines are my attempt (not great) at showing how far in the "1" is for the "10". The blue lines are where the "10" would be, using the spacing and application method shown on the breakaway500 revolver. Of course, the red numbers to SN "10" are my additions to show how far in "10" really is. I used a font size similar to the "10" to keep everything scale. So basically, if the SN 10 gun were correct, among everything else wrong with it, I would expect the "10" to lead off where the added red "3" is that I placed, not where it is currently.
The font is larger for "10" as others have said, and could even be the wrong font style for these to boot, but I would need to a loop to be sure of that.
This is called boosting, and is more common on military issue guns than anything else, where an additional mark can mean a big difference.