Dead trigger and Doubling

[Leozinho]

Dead trigger AND doubling

I have a new 9 Pro. The factory test fire was on 3/17/2011. Serial number starts with D. It has a silver striker and large sear plunger.

I installed the Apex competition trigger and sear spring (I left the striker spring stock) and re-profiled the sear just enough to take most of the “hump” or “wave” off. It’s just over 90 degrees now, if that makes sense. I didn’t reduce the height of the sear; i.e. I didn't take any metal off the top of the sear. Keep in mind that this is a Pro sear, which may have a lower height than a stock sear. Not sure.

I also polished the face of striker assembly where it engages the sear (just a polishing, no significant removal of metal). Trigger was 4.5 lbs after polishing/re-profiling sear and dropped to 2.6 lbs after installing the two lighter springs.

I did all this before I fired it, which I know isn’t the way to do it. But it’s easier for me to get to my workbench than the range, and the urge to tinker was overpowering.

Finally I test fired it, and I have the dreaded dead trigger every 5 rounds or so.

More worrying, possibly, is that it doubled and then tripled on me as well.

From doing a little reading, I suspect the weaker competition sear spring is causing the dead trigger. The theory, as I understand it, is that the weak spring is underpowered and lets the sear 'flutter' and if the timing is wrong, the sear will be in a down position and not catch and cock the striker assembly. Correct me if my understanding is wrong.

The dead trigger issue is why S&W went with the larger diameter sear plunger. (Though some have documented Pro's with the larger sear plunger that had dead triggers, the larger sear plunger mostly fixed the problem, according to what I've read. So by adding a lighter sear spring, I more or less retrofitted a known problem.)

So I’ll be going back to the stock sear spring. (Competition sear spring only reduced pull by .5 lb.)

My question is if the doubling is related to the dead trigger issue. Or did I mess up the sear and cause this, and this is a separate issue has nothing to do with the dead trigger?

Opinions? (I'm going back to a stock sear and striker assembly and will start over, which is kind of a shame because I was very happy with the feel of the trigger. But I want to know what I did wrong.)

Thanks.

Edited November 28, 2011 by Leozinho

[beastfrog]

re-profiled the sear just enough to take most of the “hump” or “wave” off. It’s just over 90 degrees now, if that makes sense.

...

Or did I mess up the sear and cause this, and this is a separate issue has nothing to do with the dead trigger?

There's your problem. Put original sear back in (or Apex sear) and use the original sear plunger spring.

[want2race]

I never use the light sear or striker springs.

If you rounded the striker at all when you polished it, or reduced the "hang down" length then you've changed the engagement of it to the sear. By reprofiling the sear, you've reduced it's height as well. Because it pivots, by reducing the length from the pivot point (you removed the "wave", which reduces length) you've reduced it's overall height which also reduces engagement. The sear angle is important. If you cut a 90* angle relative to the top of the sear, once it's installed and it pivots up to it's resting position, only the very bottom edge of the striker will engage the sear. That in itself is not so bad, but if the angle and spring rates are just right (or wrong) the the striker will push down and override the sear as the gun cycles.

Fortunately you cut the stock Pro sear. Order the Apex sear. If nothing else you can compare their angle to yours. They have gone through a couple of different sear profiles (that I've seen). But they work.

For now. Cut the front of the sear in the area that will allow it to pivot higher up, change to the stock sear spring and retest. BTW you can use a Glock orange armorer plate to inspect the engagement of the sear/striker while assembled.

[Leozinho]

Thanks for the detailed response, Shaun. That is helpful.

[kend]

We have a couple of the factory Pro sears in stock if you want to go back to that.

[Leozinho]

We have a couple of the factory Pro sears in stock if you want to go back to that.

I already ordered an Apex hard sear and another striker assembly from you this afternoon. (I did see the Pro sears you had for sale but decided to see what all the fuss was about with the Apex.)

But I've got a feeling a trigger job from a true professional might be in my future anyway.

Edited November 29, 2011 by Leozinho