Edgar, these are all the pictures I received, though I am sure Keith could provide more. Keith did say that Laminated Steel is on the rib.
For the missing hammer, one thing on these back actions is that they may use different hammers than latter guns. I believe the square cut out in the hammer is bigger were it fits on the tumbler. At least that has been my experience, but someone might know more about this than me.
Here is #46 which is similar to this #15 in many respects:
http://parkerguns.org/forums/showthread.php?t=23414
Hybrid Mode