Half cock hammer fall

[1918]

Hi All;I've never had this problem before, but I do now! I just finished rebuilding the fire control in my US Gov model 1911. I used the following parts:
Nowlin Pro Match hammer and sear
Wilson standard disconnector
Cylinder & Slide aluminum trigger w/ SS bow
The sear nose was stoned and honed to .020" using an Ed Brown jig and I stoned the appropriate breakaway relief to leave a .010"wide nose land.
The hammer was worked in the same manner, but without any special jig. Hammer and sear contact surfaces are set up the be the 90 degree standard.
The mainspring is a Nowlin 19#. The break is super clean and consistent at 3 1/4 #. There is no hammer follow when the slide racks home, stripping a dummy from the mag on the way.
But, when I set the hammer at half cock, grip the pistol and pull the trigger, the hammer falls. ???? Any ideas??
Thanks - 1918

[doctruptwn]

Did you change the sear spring it is not mentioned. The left leg of the sear spring may need some tweak since this is a new sear. Also check the the left leg is not binding on the new sear at the cross bar. Beyond that Tuner or Niemie might have other suggestions, but it sounds like you did the rest correctly.

[log man]

Hi All;I've never had this problem before, but I do now! I just finished rebuilding the fire control in my US Gov model 1911. I used the following parts:
Nowlin Pro Match hammer and sear
Wilson standard disconnector
Cylinder & Slide aluminum trigger w/ SS bow
The sear nose was stoned and honed to .020" using an Ed Brown jig and I stoned the appropriate breakaway relief to leave a .010"wide nose land.
The hammer was worked in the same manner, but without any special jig. Hammer and sear contact surfaces are set up the be the 90 degree standard.
The mainspring is a Nowlin 19#. The break is super clean and consistent at 3 1/4 #. There is no hammer follow when the slide racks home, stripping a dummy from the mag on the way.
But, when I set the hammer at half cock, grip the pistol and pull the trigger, the hammer falls. ???? Any ideas??
Thanks - 1918
A few comments, the idea of using a .020" shim on the EB sear jig is not to reduce the height of the sear above the jig to .020", but to give the stone something to slide on and not wear the jig.

Since the Nowlin hammers half cock notch is a captive style the reason you can pull the trigger and drop the hammer is most likely due to insufficient pre-travel. I must add that the half cock is a safety only and pulling the trigger in the half cock notch isn't doing your stoning efforts any favor, I know the Nowlin has a narrowed half cock, good.

Pre-travel or take up should allow the sear to fully engage the half cock notch. And it should be able to pass this test. Trigger held back push the slide back just far enough to engage the half cock notch and return to battery release trigger and it should reset.

LOG

[1918]

You are on the ball - yes I did not mention the sear spring. It is a new Nowlin match style spring. I've honed all of the contact areas of the three fingers and I'm sure that the sear finger is not binding on the frame wall. I like to put a fair amount of tension on the trigger/disconnect finger because I like to hear a nice audible "click" when sear's feet snap over the disconnector's paddle - but I can't see what that would have to do with my half cock dilemma.

[doctruptwn]

Mine and subsequently we had several others who were having problems with the half cock not staying captive. Effectively what was happening was that the sear was engaging the half cock by simply moving just enough to ride on the edge of the captive leg of the hammers half cock. ( if that makes sense)

What was causing the problem was the left leg of the sear spring was about 0.1" to long. allowing the leg to bind on the cross bar of the sear.(it you think about the sear being an H shape) Visually it was not detectable unless you happened to get the spring in a bind durring install.

here's a Link of the discussion:
http://forum.m1911.org/showthread.php?t=60454&page=1&pp=10&highlight=half+cock

Niemie had a pic on another thread that showed the spring and how much gap there should be approximately anyway.

I found it: here's the thread:
http://forum.m1911.org/showthread.php?t=63370

[niemi24s]

Here's a pic that's a little better than the ones I'd previously posted:http://i129.photobucket.com/albums/p232/niemi24s/P093160001b.jpg The sear spring's a genuine Colt.

[Hawkmoon]

If your trigger has an over-travel adjustment screw, back it out one full turn and try again. Let us know what happens.

[log man]

If the over travel screw where screwed in too far this would be cause for the sear nose to catch the half cock notch when the hammer was dropped from full cock. In this case by the OP's description the sear isn't engaging the half cock notch deep enough. The two things that will cause it to do that are mentioned, a too long sear leaf. Which I doubt on this one, but of course will cause this and could on this one, but Nowlin sear springs are on the short side, and the trigger bow not allowing the disconnector and sear to go forward enough due to lack of pre travel. Actually a third item to check out if the the trigger is loose, not under spring tension, is then the hole in the disconnector is stopping prematurely on the sear pin and can be relieved to solve this. A mix of new parts will invariably cause problems until it's sorted out. Back to you 1918?

LOG

[1918]

Well log man i think you are right - some others also.
Last night I got real lucky - seriously lucky! After about 100 rds we started a little match; my son, his boss, and me. We were shooting at 75 ft and we had pasted a 1" black dot on a white paper. We were each allowed 1 shot at a time and I chose (no particular reason) to just load 1 rd at a time in the mag. On my first attempt I closed the slide and was jolted by a fired rd. I always hold the trigger back when I close the slide so I figured that I must have somehow nudged the trigger and fired the rd. When it was my turn again I purposely aimed the pistol directly at the target. As I closed the slide another rd let fly. Needless to say that was it for me for the evening.
When I got home I disassembled the fire control and immediately saw that the center of the sear nose was battered and a good size burr had been raised. There was no way that sear could have safely seated itself on the hammer notches. The Nowlin Pro Match hammer has a captive half cock notch, but it's sides are relieved so only the center section can catch the hammer.
My only conclusion was that I had the over travel screw in the trigger moved in too far and the half cock battered the sear.
Can you imagine if I had a fully loaded 8 rd mag at the time that we were doing our little 1" dot match!! There would have been 8 rds fired in less than a second with God only knows the consequences. I was lucky.
1918

[log man]

Interesting addition, that overtravel screw will mess up a sear nose if not adjusted correctly to allow the half cock to pass the sear held back by the trigger easy to check.

But your original complaint was that you could drop the hammer from the half cock. Are you saying the sear nose was so battered that it wouldn't be held captive. Serious battering.

Considering you description of stoning the sear down to .020" this may now be good reason to go back to a new sear at this point. The reason for stoning the sear is to smooth and polish it and to check left to right contact, not to shorten it. A sear should be between .450" minimum to .460" maximum, this measurement taken with the sear pin in the sear from the bottom of the pin to the top of the sear nose engagement surface with (this is important to get the right measurement) the engagement surface parallel to the caliper jaw.

The best way to adjust the over travel screw is to remove the GS and flip the strut up out of the way and slip the MSH back in. This way there isn't any hammer tension and you can swing the hammer up and down freely. Adjust the screw in until you feel the sear nose brush the full and or the half cock with the trigger held back and back off a turn or so and check for free movement through the range. Loctite the screw, I use #290 as it's a wicking type and a half drop will do the job.

LOG

[1918]

Log Man,
Thank you for your knowledgeable advice. I've always gone by Jerry K's Shop Manual, Vol 1 and 2 for such data. Perhaps there are other resources that need to be looked at also. Any advise on where or who? I appreciate your input.
1918

[log man]

Log Man,
Thank you for your knowledgeable advice. I've always gone by Jerry K's Shop Manual, Vol 1 and 2 for such data. Perhaps there are other resources that need to be looked at also. Any advise on where or who? I appreciate your input.
1918

Ya know what, you're in the right place already, to learn, other forums as well, a lot of misinformation, but if you persevere you will sort it out. J.K.'s manuals are great, but have some misinformation also. You can learn from misinformation almost as well as good information. Many things are quite curious, but when you see/think them through ,you see the truth/ reality. The 1911 is intriguing for it's complicated simplicity. Maintain a level of wonder and answers come.

LOG