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I was lurking at another forum and read a post where a guy said he was suspicious that one of the hammer hooks in his SA WWII Mil-Spec was not engaging the sear? What does this mean and what would be the signs of this not happening? Mostly just asking out of curiousity.
 

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On the normal 1911 type hammer, the half cock notch extends all the way across, but the full cock notch is split to allow machining for the hammer strut. This means that instead of a single full cock notch, there are actually two, sometimes called "hammer hooks".

Ideally, both "hooks" should engage the sear evenly, but the ideal is not always achieved. Not only machine tolerances, but damage, wear, etc., can keep the "hooks" from bearing evenly and disengaging at the same time. This is what the guy on the other forum was talking about.

How is this detected? A gunsmith often see the abnormal wear areas, or can check engagement with something like dykem blue or with some fairly expensive equipment. It is almost impossible to detect in normal use unless there is breakage that results in a radical change in trigger pull.

Jim
 

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What that usually means is that one hammer hook is touching the sear nose a great deal more than the other one or that one of the hooks is not touching at all. For optimal performance both of the hooks should be touching the sear nose an equal amount as possible and this will result in a much more precise feel to the release of these two parts - of course all other aspects of the trigger group must be attended to properly to achieve the desired result including properly shaped hammer hooks, sear nose angle and escape angle.

It is quite easy to determine how much of the hooks are touching or if one is not touching. Take the hammer and sear out of the firearm, coat the sear nose with dykem or some other type of marking compound, put the firearm back together and cycle the firing system several times. Take the hammer and sear back out and see what the pattern looks like on the sear nose. If you have two hook marks that are almost the same size and they comprise about 75 per-cent or more of the hammer hook widths then you have a pretty sound contact pattern. If you have one heavy pattern from one hook and a very light or extrememly small contact pattern from the other hook then you will need to make some adjustments to bring the surfaces into better alignment. Finding out what type of contact pattern you have is the easy part, getting them to mate properly can prove to be quite trying at times and may require both adjustments to the sear nose and one or both of the hammer hooks.
 

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One excellent indication of a bad hammer/sear engagement is when you fire a single shot, and your 1911 goes "full auto" for three or four rounds. Don't ask me how I know that...:eek:
 
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