Light primer strikes, Apex FSS & PC slide.. anyone else have this problem?

[etwinam]

So I have an M&P full size 4.25" 9mm that I put an Apex Forward set sear on and it has never had a problem, not once.

I recently had the blessing of finding a ported performance center 5" Slide CORE. I took it to the range and had a horrible time. The gun was great and it was a blast except for a few light primer strikes.. I would say 1 of 10. I swapped out the striker assembly of my 4.25" and it cycled fine with no light strikes so I called S&W and they sent me a new striker assembly.

Fast forward to yesterday (It took 3 weeks approx to get the striker assembly) and everything going well then all of a sudden Light primer strike. So i swapped out the striker assemblies again to the old one in my 4.25" and still issues.

So I started thinking ... It doesn't have any problems with my 4.25" ... but the same striker assembly fails in the ported 5".. So it must be the USB. I have an apex FSS and the 4.25" has an Apex USB, that is the only difference. That is the only conclusion I can come to.

Someone please help to steer me in the right direction. I feel like I should just swap out the USB for an apex but is it something larger? Should I even spend the money without checking with S&W First? I mean it's only $35 but still that adds up. I'm saving to get the mount for my 6.5G conversion so just trying to avoid extra expenses.

Thanks all.

[tophatjones]

You're right, the Apex FSS does have a different striker block. You'll need to bring it over from your 4.25 slide, or buy another FSS block directly from Apex, or possibly reprofile the Smith block to match the Apex. Note: only the FSS block and sear are different, the dcaek uses the same profile as oem.

[etwinam]

For the amount of effort to swap out the striker blocks with sight removal I would just buy a new apex USB. The core is way easier to swap USB, it's located under the rmr slide. So that's my dilemma.... Guess I answered my question just talking my self though it.

I just hope that fixes my issue.

I'm hoping someone has had had this issue and can chime in. It would be greatly appreciated

[tophatjones]

Make sure you get the FSS block, ask if Apex will sell it apart from the kit. I got my info directly from them a couple years back when I asked them to sell me the FSS sear alone.

[etwinam]

I'm was under the impression the USB from Apex is all the same. The dcaek didn't change the USB. Correct me if I'm wrong but there are not multiple Striker blocks.

[tophatjones]

Afaik, there are two different block profiles, oem=daek and FSS. The FSS sear is drastically different from oem and dcaek, and changes the timing between the sear, trigger bar, striker, and striker block. The block needed to be changed as well. Best bet is to confirm with Apex.

[etwinam]

According to apex website they only sell one USB but multiple sear assemblies and trigger groups.

https://store.apextactical.com/WebDirect/Products/Details/191853

The springs seem to be the biggest difference in duty carry to fss.

Either way it appears I'm getting an incorrect connection between my fss and my PC striker block. It appears I need to swap them out. I'll put in the order tomorrow.

[tophatjones]

I'm was under the impression the USB from Apex is all the same. The dcaek didn't change the USB. Correct me if I'm wrong but there are not multiple Striker blocks.

After reading your link and the FSS page, I think you are right. The USB is the same for dcaek and fss kits and different from factory SB. It's worth a phone call to Apex to confirm though.

Did you need to open the trigger loop when installing the FSS kit? By opening the trigger loop, the trigger bar acts on the sear earlier. The sear begins to clear the striker earlier, and the striker block may be still partially in the way when the striker is released. If the USB was designed to clear earlier, it would solve your problem.

[etwinam]

I had Gunfighter tactical install the apex kit, they did it for $35. Including the sight removal and all that's a deal in my book. I'm sure they did the trigger loop, it engages perfectly on my short slide, never having an issue.

[flanel]

FYI, the trigger loop does not always need modification.

[Ksmash01]

It could be just the striker spring that may be too light.

I have the FSS kit in my 9L, but kept the factory striker spring in.

I also have the DCAEK in my FS M&P9 and my 9c, but with factory springs everywhere else but the trigger. The Apex springs in the sear, striker, and USB made everything too light.

All flawless.

[etwinam]

I just ordered a new USB and I'll install it.if it doesn't fix the problem I'll try the springs. I like the light trigger so I'm trying not to add weight to the spring.