Having worked on dozens of 1909's over the years, these are my findings. The DWM produced actions, while being more nicely machined, tend more often to be soft or exhibit signs of lug setback on the lug seats. The FMAP receivers lack the nice machining of the DWM's but have presented less often with setback issues.
Testing the hardness on those pre-WWI era receivers can be problematic. The test is usually conducted on the flat underside of the receiver behind the recoil lug. A test conducted in this location cannot be relied upon to accurately reflect the hardness of the lug seats however. It was for this reason that I routinely had any 1909 actions I was asked to build upon heat treated (Carburized).
Does this mean that every 1909 is going to exhibit setback? No. But, you never know which will and which won't.
