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Light Primer strike on M&P 40 after Installation of APEX Trigger


LilTMoney

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I installed an APEX competition trigger on my M&P Pro 40. Now i am getting light primer strikes. Not all the time, but more then it ever should. I might run 20 or 30 with no issue then have 4 or 5 in a row. I went back and installed the factory striker spring thinking that might help but still the same issue. Any insight on this would be great. Thanks.

Edited by LilTMoney
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Might be a timing issue; the ramp on the trigger bar may not be raising the striker block (round piston like part) enough at the point when sear releases striker.

This leads to peening of the groove in the striker. Examine the striker for any deformation due to interferance with the block. Also, see if by installing the original striker block the problem is resolved.  A simple solution is to close the loop at the end of trigger bar just a bit, as that delays sear release and allows trigger bar to raise the block a bit more.

Of course, it could be something completely different. Curious as to outcome.

 

Mark

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As MPOM said, it is likely a timing issue. The gap on your trigger bar loop (candy cane) is opened too far. This allows the striker to be released prior to the striker block clearing. This robs the striker of a significant amount of energy, resulting in light primer strikers. 

 

To fix it, reduce the size of the gap on the trigger bar loop. This will fix your timing issue and allow the striker block to fully clear before the striker is released.

 

If you have another M&P, that you know works fine, go dry fire it. It will make a crisp clicking/snapping when dry fired. A gun with incorrect timing will make more of a dull thud noise when dry fired (depending on how off the timing is).

 

Essentially, you are doing the OPPOSITE of this:

 

Edited by Avedis
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Ok i just got finished closing the gap on the "candy cane" i will go shoot tomorrow to see what happens. I didnt close it much. It was at .010 and i took it to .007. When dry firing, it seems good and sounds good. Not sure? Will give it a try.

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On 3/19/2017 at 5:29 PM, LilTMoney said:

Ok i just got finished closing the gap on the "candy cane" i will go shoot tomorrow to see what happens. I didnt close it much. It was at .010 and i took it to .007. When dry firing, it seems good and sounds good. Not sure? Will give it a try.

Try placing a pencil in the bore, rubber eraser closest to breech face, point up and dry fire. See how much the pencil is smacked up by the striker. Compare this distance to another M&P if you can find one.

 

Mark

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Just an update. I just shot 250 rounds through my m&p after the adjustment on the trigger bar loop with no light primer strikes. Amazing how something off 3 thousands of an inch can make that big of a difference. Thanks again for all the insight and advice!!

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  • 2 months later...

G'day from Australia!

 

I'm now having the same issue with light primer strikes with the Apex FSS and trigger kit. However, I must have put several thousand reloads through it after installing the Apex kit without any problems until a couple of months ago when the light primer strikes started.

 

The top pic is of the new striker I've just installed, the bottom pic is of the striker I took out.

 

You can see in the bottom pic that the striker shows evidence of hitting the striker block, in fact it has peened over the top edge on the side of the striker making it ever so slightly taller. I'm wondering if, over time, as the peened over edge got worse, it has started to contact the striker block even more and causing the light strike issue. With the FSS, the timing between moving the striker block out of the way and then releasing the striker seems very fine.

I've replaced the striker tonight after 8000rds and countless dry fires (And after waiting four weeks to get one from the US!) and have also set the trigger bar gap to .008". I'm a little concerned that with such a small trigger bar gap the sear isn't moving down very far at all. It is releasing the striker every time though, even when I push the slide down on the top of the slide, so I'm assuming it's far enough. I do believe it's riding down the face of the sear though.

I'll go and put a couple of hundred rounds through it tomorrow and see what happens!

 

3_zpsahswdt2f.jpg

 

21DC8819-C6C9-4DDF-A3B3-E466445D93D2_zps

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  • 2 years later...

12/05/2019

 

 I had over 5000 rounds on my M&P 9 without a single failure. After installing an apex competition trigger and spring I began to have Light Strike every 7 to 10 Rounds..... I read the suggestion on this forum about opening the candy cane to fix the timing and it was incredible.  Thank you all for helping out.

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9 hours ago, Eddy said:

12/05/2019

 

 I had over 5000 rounds on my M&P 9 without a single failure. After installing an apex competition trigger and spring I began to have Light Strike every 7 to 10 Rounds..... I read the suggestion on this forum about opening the candy cane to fix the timing and it was incredible.  Thank you all for helping out.

I think you mean closing the  opening? Point being if the striker is released too early by the sear, which occurs when the candy cane "slope" hits the sear, the trigger bar section that lifts the striker safety plunger has not lifted the plunger sufficiently to clear the striker. As the trigger bar moves further back during the trigger pull the plunger is lifter more, eliminating potential interference with the striker, which is likely the reason for light strikes.

 

Mark

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On 3/18/2017 at 3:25 PM, Avedis said:

As MPOM said, it is likely a timing issue. The gap on your trigger bar loop (candy cane) is opened too far. This allows the striker to be released prior to the striker block clearing. This robs the striker of a significant amount of energy, resulting in light primer strikers. 

 

To fix it, reduce the size of the gap on the trigger bar loop. This will fix your timing issue and allow the striker block to fully clear before the striker is released.

 

If you have another M&P, that you know works fine, go dry fire it. It will make a crisp clicking/snapping when dry fired. A gun with incorrect timing will make more of a dull thud noise when dry fired (depending on how off the timing is).

 

Essentially, you are doing the OPPOSITE of this:

 

Yes this was my issue as well until I watched this video and I also installed an extra power striker spring 

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  • 1 year later...

I have not had that issue and have not used this product, but it claims it will resolve the issue. b

 

Extended Striker Block Plunger for M&P®

After installing a custom aftermarket trigger in your factory S&W® M&P®, you may experience light primer strikes, which can lead to a failure to fire. To address this well-known issue, we offer an extended striker block plunger, which has been re-engineered to ensure positive ignition.

Even without a custom aftermarket trigger, the improved geometry of our Extended Striker Block Plunger makes a great addition to noticeably improve the feel of the factory trigger.

Fits all S&W® M&P® and M&P® 2.0™ (including Compacts) and S&W® Shield™, any caliber.

Fully machined from 17-4 Stainless. Drop-in installation.

 

https://www.edbrown.com/product/mp-esb-plunger/

 

 

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  • 1 month later...
5 hours ago, Stein2277 said:

in the video he shows a detailed procedure to open the loop on the candy cane, what's the recommended procedure for closing down the gap on the candy cane?

I dont know what Apex recommends but its easy enough. I first measure the opening with a feeler gauge, pick one 3 or 4 thousands smaller, place it in the opening and squeeze down, top of candy cane to the flat bar below with a smooth jawed pliers. The feeler gauge limits the new opening so its not squeezed closed too much. 

Rinse and repeat to get the results you want, but be forewarned that doing the above reduces overtravel, and you want just a bit.

 

Mark

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  • 4 weeks later...
On 2/14/2021 at 6:20 PM, CenTX said:

I have not had that issue and have not used this product, but it claims it will resolve the issue. b

 

Extended Striker Block Plunger for M&P®

After installing a custom aftermarket trigger in your factory S&W® M&P®, you may experience light primer strikes, which can lead to a failure to fire. To address this well-known issue, we offer an extended striker block plunger, which has been re-engineered to ensure positive ignition.

Even without a custom aftermarket trigger, the improved geometry of our Extended Striker Block Plunger makes a great addition to noticeably improve the feel of the factory trigger.

Fits all S&W® M&P® and M&P® 2.0™ (including Compacts) and S&W® Shield™, any caliber.

Fully machined from 17-4 Stainless. Drop-in installation.

 

https://www.edbrown.com/product/mp-esb-plunger/

 

 

 

On 2/14/2021 at 6:20 PM, CenTX said:

I have not had that issue and have not used this product, but it claims it will resolve the issue. b

 

Extended Striker Block Plunger for M&P®

After installing a custom aftermarket trigger in your factory S&W® M&P®, you may experience light primer strikes, which can lead to a failure to fire. To address this well-known issue, we offer an extended striker block plunger, which has been re-engineered to ensure positive ignition.

Even without a custom aftermarket trigger, the improved geometry of our Extended Striker Block Plunger makes a great addition to noticeably improve the feel of the factory trigger.

Fits all S&W® M&P® and M&P® 2.0™ (including Compacts) and S&W® Shield™, any caliber.

Fully machined from 17-4 Stainless. Drop-in installation.

 

https://www.edbrown.com/product/mp-esb-plunger/

 

 

I hope this will do it. For only 30 bucks, it's worth a try. I own a M&P 40 with a performance center kit that ran flawlessly before I decided to get a better trigger- Apex Flat face. Now I have the same light primer strike issue, about 5 for every 50 rounds I shoot, that's really annoying.

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