For those who don't know, the model 25 is one Smith that does not follow the "progression of change" as there are two main forms, the 25-2 is .45ACP, while the 25-5 is .45 Colt, never encountered use of another code. Take careful note if you are offered an "S-date" 25-2 as manufacturing quality slipped a bit with them. Mine was used, but not shot much and on examination there was a burr on the edge of the side plate that had scored the hammer finish, and the forcing cone had not been cut at all, only deburred. Fortunately I have all the tooling to correct these issues and it truly does shoot with best match guns.
Dr Jim