Help! P320 Take Down Issue

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Ruckus

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Hey everybody - I've been lurking for a bit and getting lots of great information from the site. I was able to complete my first MUP-1 over the weekend with the resources I found here.

I'm having an issue and was hoping I could get some insight.

I have an AXG grip module with an M17 slide and a LPK from US Patriot. Everything on the gun seems to work properly besides the take down action.

In order for me to remove the slide, I have to pull the trigger or let the slide slam home from the force of the RSA.

With the FCU removed, I can see the safety bar stuck in the far forward position and it won't return to its normal position without me pulling it slightly away from the FCU.

The spring looks to be seated perfectly fine and I spent a good amount of time cleaning all of the holes, deburring, and then polishing the MUP-1 before assembly.

Thanks for any help!
 
A little more information after tinkering with it some more;

With the slide off, turning the take down lever drops the sear like it's supposed to. It's just not dropping it far enough to clear the striker.

Once I remove the slide by pulling the trigger, the take down safety bar gets stuck and I have to manually press it forward with my finger to reset it.
 
Did you ever sort this out? It is hard to diagnose without pictures. As you probably know, when you push the takedown safety bar rearward, it will not move forward until the slide release lever is lifted upward away from the frame. If the slot in the rear of the frame is rough, the takedown safety bar will not easily move forward even when the slide release bar is lifted up. Inserting a magazine will force the takedown safety bar into its forward position. It sounds like the takedown safety lever is not moving rearward enough to completely disconnect the sear. I wonder if it is bending slightly when pushed rearward instead of moving all the way back to fully disconnect the sear.
 
RobKap said:
Did you ever sort this out? It is hard to diagnose without pictures. As you probably know, when you push the takedown safety bar rearward, it will not move forward until the slide release lever is lifted upward away from the frame. If the slot in the rear of the frame is rough, the takedown safety bar will not easily move forward even when the slide release bar is lifted up. Inserting a magazine will force the takedown safety bar into its forward position. It sounds like the takedown safety lever is not moving rearward enough to completely disconnect the sear. I wonder if it is bending slightly when pushed rearward instead of moving all the way back to fully disconnect the sear.
Click to expand...

Thanks for the reply. I will try and get some photos uploaded but I'm not sure they will show too much.

With everything disassembled, it looks like it operates as it should. The sear drops when the takedown lever is turned and like you said, it pulls the safety bar back far enough that it allows the slide release to notch into the hole.

If I had to guess, I believe the striker, sear, or FCU/rails are slightly out of spec and it's preventing the striker from clearing the sear in its take down position.

I bought the LPK from US Patriot (for a really good price) and was hoping they just have worse tolerances than factory. I plan to order an OEM TDL and sear group from Sig Sauer Parts to see if that fixes the issue.

Good news is that the pistol shoots great!
 
I have used the same USPA LPK several times and this is the only LPK I have used. The only issue I seem to run into with that LPK is that the #32 hole for the sear pin is consistently undersized for the pin provided. I have not determined whether that is an issue with the cobalt bit I am using or the pin provided in the kit. I end up having to re-drill those holes and move the XY vise a bit to get the hole the correct size to fit the pin.

I suspect that your problem with the takedown lever has to do with the slot you created and/or how it fits into the grip module. I find creating the slot for the takedown lever to be one of the more challenging aspects of this build. I did one where the outside surface around the slot ended up with rough spots/edges and the takedown lever would hang going forward. With that particular build, the behavior of the takedown lever changed in different grip modules. In a new module, the takedown lever would not release going forward until I manually pushed it forward or inserted a magazine. After the grip module was worn in by turning the takedown lever until my finger was raw, it worked fine. I then switched to a new Wilson Combat module and had to repeat the experience and it was even worse. In the end, I am not sure if this is due to friction around the takedown lever (which I tried to polish out) or just that particular cut for the takedown lever slot, or something else altogether.

I was asking about pictures to look at this slot and the rear rails. I suspect replacing parts will not fix this problem.

Do you have a polymer grip module to try the FCU in? Can you see rub marks inside the AXG module where the takedown lever might be rubbing against the inside of the module?
 
Are you referring to the slot that the spring and safety bar are in? I meant to reply about this in my last comment but I guess I forgot.

I did take the FCU apart and worked on that slot a bit to open it up a little more with no success.

I get back in town on Tuesday and will take a picture of that to get your opinion.

And unfortunately, no. The only grip I have is my AXG module.

And again, thank you for taking the time to try and work this out with me.
 
That is the slot I was talking about. Since the takedown safety lever appears to function normally outside of the grip module, it sounds to me like the issue is the interface between the outside of the takedown safety lever and the inside of the grip module. There are a lot of reports online from owners of new P320's complaining about issues with the takedown safety lever binding, especially when releasing on reassembly. It would be worth trying a worn-in polymer grip module for comparison before you make yourself crazy swapping FCU parts. I wonder if you can get a used module cheap on ebay. Another option is to inspect the inside of the grip module for wear marks and then polish those areas.
 

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