If the sear hook on the hammer were to break, the sear would be captured by the half-cock notch preventing an accidental discharge. The stud that locks the sear will also not allow the hammer to fall if the safety is engaged.
Eddie, that brought back a memory. When the NRA authorized semi-automatics in PPC competition I decided that I'd give it a try. We had a bunch of match 185 grain SWC FMC in the bunker and the armorer had just finished a 1911 that would group into 1.5" at 50 yards. I practiced diligently for weeks before the match. At the match I was assigned the far right firing point so that my empty casings wouldn't rain down on other competitors. I had been averaging 1984 out of 1500 which wouldn't win, but would be great fun in any case.
Match one was 12 rounds in 25 seconds at 7 yards and then at 15 yards. Seven yards was all X's which was a good start. The NRA required that the semi-auto be shot empty before any reload so that the range officer could see that it was empty during the reload. At 15 yards I fired the first six, dropped the magazine into a large bucket, reloaded and when I pressed the slide release the slide shot forward as did the hammer which was immediately followed by a very unexpected "Bang." The UD stuck the target in its right arm. I somehow got the remaining five into the ten ring, but only barely as I was shaking.
I was quite down-trodden as we went back to score. It was buddy scoring and a police woman next to me scored it 240. (Perfect score) It was not easy to point out the arm shot. (Score = 230)
I hoped I could still post a respectable score, but I had to align the sights each time I dropped the slide, (Just in case) and my front sight was a blur for the rest of the match since I couldn’t stop shaking.
The armorer inspected the .45 and stated that he had reduced the half-cock notch to protect his trigger job, and when the slide went forward the hammer followed and sheared the notch.
He then put it in the Ransom rest with five rounds in the magazine and pressed the trigger. What followed was a complete surprise. It went “full auto” with four of the five rounds going over the trees!
I felt quite badly about the match score, but I was very grateful that the 1911 hadn’t gone full auto during the Regional.
Respectfully,
kent