I have owned 3 model 12's. I liked them and carried a 2 inch nickel plated model 12 with square butt grip frame. It was well made and shot well for me. I would occasionally use +P ammo, but was worried about frame stretching, so mostly I carried the old FEDERAL Nyclad standard pressure 125 grain jhp. I tried the HORNADY 110 grain FTX Critical Defense ammo, but they did not shoot to my point of aim. It was a great gun for wearing on my hip when I went for an after dinner walk.
I also tried some DOUBLE TAP standard pressure ammo sold under the COLT name. This ammo had a much more noticeable kick and bright flash. It is listed as standard pressure, but I would not shoot it in my model 12 again. It works fine in a steel frame like my model 15.
The single biggest problem with the model 12 is the selection of standard pressure ammo. I consider this gun to not to be up to a continuous diet of +P which limits your ability to practice. The 110 grain FTX Hornady should work and is available, but did not shoot to the point of aim for me.
The DOUBLE TAP is plenty powerful, but I worry it may wear the model 12 too quickly.
Winchester had a standard pressure 130 grain jhp in their TRAIN & DEFEND line, but I have not seen any on the shelves in years.
That is my take on this otherwise excellent revolver. I prefer it to the COLT or TAURUS as neither of those had as smooth a trigger as the model 12.
Now I just carry a GLOCK 42 in .380ACP. More rounds, weighs less and I can easily pocket carry the GLOCK.
OH, and I strongly recommend a good pair of rubber grips. Mine sported HOGUES and it was a huge improvement.
Jim