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  1. #1
    Roshi is offline Junior Member
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    Question Hammer drops to half cock

    I have an old (1961) Sistema Colt which has a poor to fair exterior and good to very good interior, all original parts. I have put about 200 rounds through it.

    Today at the range on several instances when the trigger was pulled the hammer dropped to half cock. I then thumb cocked the hammer and when the trigger was pulled, th pistol fired normally.

    Seemed to only happen when I was using a two hand grip.

    Thoughts?

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  3. #2
    milquetoast is offline Member
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    Worn parts (sear, hammer, sear spring). Dangerous. High priority. Gunsmith, ASAP.

  4. #3
    Roshi is offline Junior Member
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    Please Explain

    I'm not sure this is as dangerous as you imply. The hammer only falls when the trigger is pulled. Three or four times out of a hundred it only falls to half cock instead of striking the firing pin. The trigger pull is consistent, around five or six pounds, even when the fall to half cock happens.

    If the sear or hammer were worn the trigger pull would be lighter and the hammer could potentially drop without pulling the trigger.

    The hammer never follows the slide forward so the disconnector is OK.

    How is the sear spring a potentail culprit? Is it causing the sear to reset before the hammer falls past half cock?

    I'm not trying to dispute your knowledge, just want to learn more before I spend more on a gunsmith than this pistol is worth ($250).

  5. #4
    Roshi is offline Junior Member
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    Sear spring?

    I have duplicated the problem dry firing and it seems to be caused by the grip safety sticking. I'm thinking this is related to the leaf trigger/sear/grip safety spring which is obviously new and was likely replaced by the gunsmith who serviced the psitol before I bought it.

  6. #5
    milquetoast is offline Member
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    It's dangerous two ways: One is if somebody is trying to kill you (which is why we have pistols, after all), and you press the trigger and nothing happens. That would suck. The other is, if it doesn't get fixed, it could get worse, and the pistol could go full auto, which can send bullets in directions you don't intend.

    A defective sear or hammer is going to cost money to fix, maybe a hundred bucks or so. Basically, you are talking about the price of a trigger job, plus parts if the old ones are defective.

    I would not fool around with it.

  7. #6
    hawcer's Avatar
    hawcer is offline Member
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    Do this easy test.

    With the gun unloaded and gripped in you firing hand,pull the trigger and be sure the grip safety is pressed.Now,cock back the hammer and let it return with a slow controlled motion with your other hand...the only thing you should feel is the spring tension.If it catches at any time you trigger may not have enough travel to totally disconnect the sear.Things to look for...Dirt or debri in the magazine well around where the trigger sits.Damaged or distorted trigger bar(s),or the magazine may be obstructing the trigger travel.

    It seems to me that you have enough travel to disconnect at the "full cock" position that has been well broke in and catching at the "half cock" position.

    Clean everything and retest before waisting any money getting it repaired.
    --This is just my opinion--

    Do whatever feels like the safest action to you.I hope you get it figured out.

  8. #7
    Roshi is offline Junior Member
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    Thanks

    Thanks to both of you for the info.

    This pistol is a plinker not an SD gun. The disconnector is fine so I'm not worried about full auto. I had a new Kimber go full auto on me years ago. Actually not as uncontrollable as you think. Made me wish I had a thirty round mag and a selector switch.

    I will try what you have suggested hawcer. Dirt, trigger bar, and magazines are not an issue. The pistol has been detail stripped and cleaned. The trigger bow and mags were checked due a mag binding problem that I cured by removing a burr on the frame.

    The trigger actually has a bit of over travel and a "clicky" feel and sound after the hammer has dropped and the trigger is pulled with the hammer down.

    My gut feel is this is some kind of interference between the sear spring and grip safety.

  9. #8
    hawcer's Avatar
    hawcer is offline Member
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    If you are able...remove the mainspring housing and inspect the sear spring for broken /bent "fingers" or possibly being installed incorrectly.

  10. #9
    Roshi is offline Junior Member
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    Done

    Quote Originally Posted by hawcer View Post
    If you are able...remove the mainspring housing and inspect the sear spring for broken /bent "fingers" or possibly being installed incorrectly.
    I have inspected it and it looked OK. However, I have not pulled the MS housing and kept the grip safety in place. This may allow me to see if there is an interference.

    Many years ago, I refurbished an old 1911 and had an issue with the grip safety when using the latest style sear spring. Installing an old style spring cured the problem.

    Worse comes to worse, this Sistema came from Gander Mountain with a one year warranty.

  11. #10
    Roshi is offline Junior Member
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    Fixed

    Replaced the disconnector, not the problem.

    Replaced the sear and sear spring, problem solved. Also installed a new hammer pivot pin to eliminate a bit of looseness.

    Now everything works as it is supposed to and the trigger pull is a bit lighter as well.

  12. #11
    milquetoast is offline Member
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    Have you fired the gun since the parts were replaced?

    Normally, sears don't drop into a 1911 without precise fitting. Usually, they come out too light (not square, or not full engagement), or too heavy (angle too steep). Not saying it can't happen. I did it once, about 25 years ago, when a new out of the box gun cracked the sear on about round 4. Dropped in a spare, and the gun has been working fine since, with a 4.5 pound pull!

    Still, it's a chancy business. Before trusting it, you might want to load only a couple per mag, in case it decides to go full auto. If it works as intended, good for you; you won the sear lottery.

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