Hi Along, sorry I didn't respond to your post. There are a number of great builders here who are willing to help, so just keep trying and asking questions. I took a couple of pictures I hope will explain my question about the necessity of the hammer being trimmed back
I know it's hard to see, but the contact patch from the firing pin is almost centered in the hammer's face, and it does make a good contact - nice and square. The next picture is a side view of the hammer and you can clearly see the mark I made to indicate where the hammer strikes the firing pin.
My idea was to leave about 1/8" above the contact area, and then trim the hammer back into a gentle arc to remove the excess metal that's hanging up on the bottom of the bolt. I have seen AR hammers before, but this one has a hook on the tail of the hammer that I haven't run across before. I'll end up cutting it off as part of the trimming. We need to have some of the more experienced builders give we
s a little more detail on some of the finer points of the bolt assembly and fire control group. The only build file I saw anything about trimming the hammer was in the Mechwarrior posting, and only because he had trimmed too much and had to weld up the face. that's the great thing about steel, if you cut too much you can always add more metal back on.