Hammer de-cocking on 1911


General Disarray
October 16, 2007, 12:32 AM
I just acquired a beautiful Dan Wesson PM-7 1911 :p that had an SV hammer/sear/ disconnect/trigger put in at CZ's custom shop. The grip safety had been deactivated by placing a small piece of rubber inside up under the main spring housing. Well, I wanted to have that safety back on, so I backed out the pin and let loose the magwell to realease the piece of rubber. I took it apart further than I think I needed to. When I took it out the next day the hammer would be de-cocking itself 2 times out of ten after the slide had automatically cocked it. I didn't know it wouldn't hold the hammer back if I manually cocked it, and when I did and let go the hammer dropped and the pistol fired the round, and the hammer was still down yet again. It was the scariest thing to ever happen to me with a gun in my hand (I know, I'm lucky). :uhoh:

I put it down for a bit. I did activate the slide then dry fire it a dozen times, and several random times the hammer de-cocked. I then ran several clips through it and it never did the decocking thing again. I was wondering why this might occur, and what I should look for to be happening inside the Main Spring Housing?

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Jim Watson
October 16, 2007, 08:01 AM
Maybe UNDER the mainspring housing. The sear spring is retained by the mainspring housing and it could have shifted while you had the MSH out. Maybe it reseated itself when you shot. It would be smart to learn how to get those parts back together right.

October 16, 2007, 01:00 PM
I find it very hard to believe that the CZ custom shop would de-activate a 1911 grip safety. And if they did, that they would do it by placing a "small piece of rubber" inside the gun!

What effect that would have anyway is hard to imagine, other then it might compress the right arm of the flat spring and just allow the grip safety to flop around.

Anyway, if there was a piece of rubber pressing against the sear spring when the hammer & sear were set up, you now have a bigger problem. The sear & hammer notch have been cut too shallow, and are probably beyond repair.

I would be on the phone to the CZ custom shop and demand they fix the gun properly with all new parts.

And leave the rubber thing out this time!


October 16, 2007, 01:52 PM
Did you buy it from CZ or used from somebody? The rubber thing sounds extremely bogus to me.

General Disarray
October 16, 2007, 01:58 PM
No, I bought it used, and the owner had put the rubber gasket in. He just had it wedged in there, and the saftey was held down, it didn't "flop down", but stayed down.

RCModel, why would the "sear and hammer be cut too narrow"? You mean from wear from shooting it that way?

October 16, 2007, 02:31 PM
From what you said, I was operating under the delusion that the CZ shop had done the work.
I assumed they had cut the hammer hooks too shallow, or at the wrong angle to make up for the tension the rubber was putting on the sear spring.

However, if the hammer is falling all the way, and firing rounds when the slide is released, you have a big problem.

If the S-V hammer is allowing that to happen, either the safety intercept notch is broken off, or the sear spring is totally out of whack and not holding the sear back against the hammer hooks.

Regardless, after it has done it a few dozen times, the sear and hammer surfaces have been damaged to the extent they will need to be re-cut to restore safety.


October 16, 2007, 03:39 PM
Just in case it's not clear - put the pistol in the hands of a reputable gun smith - I'd suggest field stripping to prevent any confusion and possiblity of future accidents until the pistol is repaired and tested. CZ may be willing to cooperate with doing some work as warranty or safety related but as I read this story has no obligation beyond giving fair value for money.

It is possible to learn to do everything yourself starting by reading the Kuhnhausen books and other publications and buying assorted tools - including for many of us magnifying visors and such to allow critical examination and proper measurement of the parts. But this will cost more than paying for one or (even two) proper repair(s) even given the outrageous price issues with shipping handguns around the country.

There are many fine instructions for detail stripping and reassembly floating around including on this board. I particularly like the suggestion by one of the wisest members to take something off, put it back, take 2 things off put them back and so it goes by sections rather than follow the directions from beginning to end the first time and be unsure how to put everything back together at the end.

There have been some suggestions among folks with some legitimate claim to be high speed low drag that for people whose hand for whatever reason does not depress the grip safety well - more common with some modern theory high thumbs grips - a small piece of black rubber/plastic to friction lock the grip safety is a useful field expedient. The idea is that if the pistol is used (in a rightous shooting) the forensic people will strip the pistol, miss the black against the blued parts and lose the piece so the pistol then will test as unmodified. Of course a grip safety can be set to release early in the motion and so avoid any such issues - that's why it is a field expedient if that.

General Disarray
October 17, 2007, 12:32 AM
rcmodel, the round fired when I tried to cock it manually, and then when it didn't hold the hammer it dropping fired the round. It didn't do that when I cycled the slide and it decocked itself.

Nontheless the whole matter is disconcerting. I was hoping that I didn't reset something properly and someone here would recognize it. Thanks for the help.

October 17, 2007, 01:39 AM
Instead of saying it "decocked" you can more accurately describe this condition as "hammer follow". The sear is not engaging and it allows the hammer to follow the slide as it returns to battery. Search this forum for more information on the causes and corrections, usually involving a tweak of the sear spring. (After making sure everything was assembled properly, of course.)

If it was a custom tune there may indeed already be damage to the sear surfaces that will require professional help.

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