I have notice some 3913's have stainless triggers but mind has a black trigger. Are they both made of the same material and why would they use two different triggers on the same model pistol?
Not 100% sure on this, but I believe the black colored triggers and hammers were on later production guns, whereas the earlier ones had the silver colored ones. Not sure what date the change took place.
And I believe TSWs have different colored triggers (hammers too) than "regular" 3913s. Somewhat like the difference between the 3913 and 3953 that I have (below):