Took the day off work today...and I think it's going to be "trigger day". I just finished reading a copy of TM 9-1270. I also found a copy of Campbell's book. I miraculously found a used one for $30 online amongst other prices from $300 up. Surprisingly it was signed!
Attachment 117028
Anyone know Edwin W Busch (or Besch, depending on how one reads Clark's cursive)? I see that Mr. Campbell has posted here in the past.
Anyway, there is a nice summary of what I found in the TM. Both were a little confusing at first on their own, but gave plenty of clarification to each other.

Before I get dozens of posts about trigger worriers...thanks for your concern. I have a brand new trigger/sear set ready to go. I'm playing with restoring the original trigger. Take a look above. In addition to the rust coating the shoe, which has now been ground out and polished, material was welded on the front nose to permanently set the trigger after the first stage. It pulled a crisp 4.5lbs, but I don't like not having a first stage. Furthermore, that kind of alteration is a sloppy expedient, and bypasses the designed safety mechanism completely, rather than refining it. So, after hours of stoning and polishing last night, I have that weld fully removed, and reshaped to match my other trigger. Thankfully, whoever did the trigger job was too lazy to touch the humps. Rifle was't fired much because the bluing is still very intact on the receiver contact points. I'll take pics if I'm successful, and maybe even post my how-to.