Actually, this is a 15. The model 12 is the more unusual looking pre-cursor to the model 15. Big honkin adjustable sights, and a barrel nut that looks like a gear at the muzzle end, though also with the 'pork chop' barrel shroud. The 12's (and 11's) were only made for a short time and were replaced by the original pork chop 15's, which are nearly identical to the final configuration - the 15-2. There were 15-1's in there as well, but I think they were more of a transitional model.
This is my first pork chop, all my other Dan's are -2 era guns