Yep, bobbed hammer DA/SA. Yours is a twin for the one on my belt right now.
Mine has the same serial prefix, just a few numbers later. Nice slick configuration for a commander sized 45.
Is yours decock only? The spurred 4506 hammer will fit.
I'm curious, why do you want a spurred hammer?
Doesn't get any better than that in a S&W 45. Regards 18DAI.