P320 won't go into battery

[jeffm_norcal]

I got a custom shop FCU to build a new gun around.  When I put it in my X series full size (all stock parts) the slide won't go all the way into battery.  It holds back a bit under an 1/8 of an inch and feels like it is hitting something solid.  Has anyone run across this problem?

[D_B_X]

If this only happens when you rack the slide by hand and not very forcefully, then it is not entirely uncommon. It does not affect shooting and generally goes away after a while. Try a different grip module -- it may/may not make a difference.

[Boomstick303]

I would contact Sig.  I have numerous P320s and the only time I experienced this is when I also built a P320 using the custom shop P320 FCU.  The reason there was an issue was due to the barrel being a Ti-Nitride and the tight fit with the aftermarket Grey Ghost Precision slide.  I had to follow specific break in instructions from Killer Innovations in regard to the barrel, for that barrel and slide to break in together.  Otherwise all of my P320s have never exhibited this behavior.

 

If you are using all stock Sig components the gun should work without a hitch as long as you have assembled it correctly.  

Edited September 20, 2021 by Boomstick303

[jeffm_norcal]

All the parts are new sig, with 300-400 rounds on everything except the custom shop FCU.  It is not that it is slightly out of battery and then you can push it closed, it goes to the last bit and stops hard.  No amount of force (that I'm willing to apply) will make it close.  

[D_B_X]

24 minutes ago, jeffm_norcal said:

All the parts are new sig, with 300-400 rounds on everything except the custom shop FCU.  It is not that it is slightly out of battery and then you can push it closed, it goes to the last bit and stops hard.  No amount of force (that I'm willing to apply) will make it close.  

Oh.. that's something different... Do you have parts to swap to see if it is the slide or FCU that causes this?

[Boomstick303]

Can you take a picture of the bottom of the slide?  The side that mates up with the grip module.

Edited September 20, 2021 by Boomstick303

[ahfox32]

I have a stock legion (other than TSAs trigger/action work) with a Sig custom FCU and it works perfectly. 
 

Somethings no right with the gun. I’d not shoot it till u get this sorted. 

[jeffm_norcal]

The stock FCU has no problem, just the custom shop one which does this.  If you look closely at the out of battery pic you can see that the hook on the striker is sticking out of the back a bit and the plate on the slide hits it.  With the stock FCU the hook goes in further so no problem.  SIG says send it back, given the sketchy reputation of these guns I suppose that is what I'll do.  Still interested to know if anyone else has seen this problem or has an idea of what is causing it.

[jeffm_norcal]

So problem solved.  The "Custom Shop" FCU did not have the pin for the manual safety installed.  With QC like that it's easy to see why there are so many complaints about these guns.  Hopefully this will help people who have the same problem.  Thanks for all the replies!

[D_B_X]

That's the safety lever pin. (Not for manual safety)  I never saw that thing missing... Seriously?

 

I wonder what is holding the safety lever on the other side. Wouldn't it just fall out?

[Boomstick303]

You have to watch a couple of the pins as 1-2 of them can fall out pretty easy. It’s something that could pass QC then fall out during packaging unfortunately. Sig has improved many of the pins from earlier models to where they “lock” into place and have to be forced out with the proper tool to remove them. The safety lever pin is not one of them. I am always mindful when removing the FCU to watch for dropping pins as with reassembly. I hold the grip module and FCU vertically during dis-assembly and assembly. 

 

To be honest not sure how the could design this pin in a way to “lock” it into place. Yes a missing internal safety lever would be a concern if that pin is missing.

 

 On a side note the P320 internal safety lever does not have a safety return spring as part of the FCU assembly. They removed that spring a few generations ago. So if you watch an older trigger install video that references that spring it was probably never there to begin with. 

[jeffm_norcal]

I was able to find a few other posts from folks who have received an FCU without this pin.  It really does speak to some QC problems in their manufacturing process.   One of the other things I found as I went down the rabbit hole was the video below.  Of course the gent who posted it has an agenda, but when you look closely at the machining on a lot of these parts it does make you wonder.