Hammer fall to half cock after fired

[Benevolence]

Hi all,

 

Just did first test firing of a 9mm 2011 I’ve been building and I am having some issues; I believe they are not related to each other but I may be wrong. To note the related parts, I have a Wilson Combat square profile firing pin stop, Ed Brown perfection sear, Ed Brown Barstock Hardcore hammer, Fusion slide, 80% Black Mountain frame I machined to finish. 

 

When firing, I am often getting light strikes, despite a stock, heavy mainspring. Furthermore, the hammer often falls to half cock after firing a round, but not when cocked manually (with or without trigger pulled). Also, the hammer will have an audible ‘click’ if I press the hammer back the slightest bit after racking the slide (with or without trigger pulled). I believe this is the sear engaging fully, from a ‘partial’ position. 

 

I believe there could be several causes for this but I could use help in narrowing it down if possible. One could be the overtravel screw was not screwed in much, and allowed for the leaf spring to lose pressure on the sear after disconnector pushed down? The other would be a sear that is too long on the side that engages the hammer hooks? Lastly, perhaps I didn’t deck the top of the frame enough and the slide is sitting too high to fully cock the hammer?

 

I’m a bit perplexed by the light strikes, perhaps square profile FP stop not allowing the hammer to hit the FP hard enough? My previous 2011 build did not have these issues. 

 

Thanks in advance for any input!

Edited August 1, 2020 by Benevolence

[konkapot]

Not an expert. At all. 

 

1. Assuming the ammo is not a variable; it's good ammo that works in other guns. 

2. I do not think your overtravel screw theory is viable. 

3. For grins/giggles I would take a firing pin stop from a working gun and install it; hopefully isolating that part of the problem. 

4. The audible click when you press the hammer after racking the slide back is troubling; IF that sear isn't fully engaging, AND you are having halfcock issues, there's a potential safety issue there. 

 

The gun is obviously clean, but I'd take a close look on the interior of the hammer/s/d chamber and make sure nothings binding or getting hung up. 

[zzt]

If you bent the trigger bow tabs to lessen pretravel, flatten them out.  Back the overtravel screw out so you have a lot of overtravel.  Then try again.

 

Check to make sure the hammer strut is not rubbing on the GS.  Some GS and struts are not compatible.  Check to see the FPS is correctly centered and allows the FP to move freely when in battery.

[Benevolence]

Thanks. I did have the thought of a burr in the sear/disco channel slowing down the sear reset. I may aught to clean that out more. The overtravel screw thought was that once the slide pushes the disco down, the trigger bow can push the left spring leaf off of the sear leg if it is permitted to pull too far back. I have extensive pre travel at this point, so I don’t think that is it.  I didn’t think about the GS/hammer strut; I’ll take a look at that. I may buy a sear jig since I’ve two at this point. 

[cheers623]

Sometimes that audible click sound when pulling the trigger during take up is the disconnector moving in the frame hole. I’ve had that happen on a number of trigger jobs and one of the ways to eliminate it is the EGW ball-head disco that you fit to the frame hole. It’s a bit of a pain in the ass...but worth the hassle. 

[Benevolence]

Thanks for the input. I hadn’t considered the disconnector. 

 

After some tinkering, I believe it could be either the sear is rubbing on the hammer near half cock or the safety plunger is pressing on the safety to raise the safety slightly, and the hammer is rubbing on the safety. Or both. I’m not quite sure what the best method for the safety rubbing is, perhaps filing more off to make better safety clearance. I’ll try a few things and report back. 

 

Edit:  I think it’s the latter. And not to mention the sear/leaf spring left leg isn’t doing a great job of sitting on the sear leg. 

Edited August 2, 2020 by Benevolence

[dons]

Re: Light strikes.  Make sure your firing pin is not bent: don't ask me how I know!

 

[Vmax606]

Put a layer of tape on the hammer surface, cycle the slide and press down on the hammer.

 

Is the "CLICK" still there? If not then either the sear nose or the hammer hooks are a little too long. 

 

Not sure about the light strikes problem.