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SIG SAUER - MCX Mandatory Carriage Assembly Replacement Program

87K views 472 replies 120 participants last post by  Ranger3 
#1 ·
#445 ·
Shot my MCX this past weekend. Everything worked good. Didn't notice any scoring to the upper and firing pin retaining pin wasn't sticking out too far.

Noticed the recoil springs are stiffer (new perhaps?). Also, a bit harder to close the upper and lower since the plastic spring cup needs to be pushed in a bit to clear.

Shot a couple of mags suppressed and unsuppressed and functioned flawlessly.


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#447 ·
I wanted to share my experience since I just received my upgraded MCX. Originally when I registered for the recall I mentioned I had a Geissele SD-E trigger (basically an SSA-E with a flat face) and they told me to hold on to my rifle and to just ship in the BCG. So I waited for the box which eventually came and I shipped my BCG. I called a few weeks later since I hadn't heard anything from them and asked again about trigger compatibility. It was then Sig requested I ship my rifle to them.

I received the rifle back recently and the work note mentioned they removed my SD-E trigger and installed an SSA. They also apparently dipped the entire rifle in a vat of oil requiring me to break down and clean the BCG. During disassembly I noticed the new firing pin lock had the G stamp, making it apparently Geissele compatible. I called Sig and mentioned my SD-E trigger and the customer service rep I spoke to said it "might work". AFAIK the hammer geometry are identical between the SSA and SD-E triggers. I also emailed Geissele since their website specifically states the MPX and MCX are not compatible with their triggers so I'm confused Sig would install one. This is their response:

Thank you for contacting us. In regards to our stance on our triggers in the MPX and MCX, as the industry grows, there are more and more AR variants out there that accept AR15 fire control groups. Each one is different and though we would like to, we have not tested our AR15 triggers with any of them. What we know about our triggers in the MPX we have learned from feedback from our customers. From the beginning, our customer service representatives have explicitly told people that we have not had any experience with our trigger in the MPX/MCX. We have stated that forum users have claimed to have success but we cannot confirm their success. We have never strayed from this and have never confirmed our trigger work in those platforms, and have always maintained that our triggers were designed to function with a mil-spec M4 carbine. With that said, the MPX has a very fast action, which is why the MPX ships with the trigger bridge, to protect the fire control group from the action. The MPX was designed to be used with the trigger bridge, our triggers were designed to be used with AR15 rifles using mil-spec components. While the MPX combination will work for a while, it will eventually fail. We want to be clear with our customers on this, and also have them know that we are working on an MPX specific trigger. We do not recommend using our AR15 triggers in these variants as it will void our warranty.

Going forward, rebuild kits for our AR15 triggers installed in the MPX/MCX will be available for a fee. The SSA-MPX dedicated trigger group is currently in development and will incorporate a trigger bridge to alleviate the current issues. It is slated for release in 2017. Unfortunately the SSA-MPX trigger is still in development and the price has yet to be determined as well as a definitive release date.

As for the recent MCX recall and the new carriers, we have just recently heard of this recall and we are still working out all of the details. Right now, we cannot confirm this information about the carriers and the compatible of trigger groups Sir. Once we get more information about this issue, we will let everyone know.

Again, for the MPX, we do not recommend using our AR15 triggers such as the SSA as it will void the warranty. We recommend waiting until the SSA-MPX trigger is complete. This trigger group will have an incorporated trigger bridge to alleviate some of the issues with the MPX and will also be compatible with the MCX. The SSA-MPX has not yet been released. The slated release is 2017.

I hope this helps. Please Let us know if we can be of further assistance.
For the record Geissele responded to my inquiry a few hours after I submitted it and their response was thorough. Unfortunately it didn't shed any light on why Sig would put their trigger in my rifle and by now I'm super confused.

Only thing to do at this point it take it out to the range and test it. Today I did that with 220 rounds through the rifle without failure. I tested the Okay Industries 30-rd, Magpul Gen 3 and Magpul Gen 2 Windowed 30-rd, and a 40 round Gen 3 Magpul. The bolt locked back on all of these mags when empty. I also compared the first and last round out of the rifle to check for weak primer strikes and it didn't appear that the firing pin strike indent diminished. For comparison I took a photo of the same ammo (Lake City XM193 which has a hardened primer I believe) fired from a PWS MK116 (left) and the upgraded Sig MCX (right). The firing pin strike looks comparable - maybe someone with more knowledge can comment but this doesn't look like a weak strike to me.
 

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#448 ·
Yeah PT857, looks like you're good to go. A bunch of us are running Geissele triggers in our MCX rifles, and we'll see how they hold up over time. Their trigger bridge seems like a better option than modifing the hammers to me...

Enjoy your rifle!!

Cheers
 
#450 · (Edited)
I'm in the process of getting the MCX bolt carrier replacement concluded. And the mystery is why SIG sent me a new hammer. The very nice CS lady didn't tell me and I just said sure, sent it. She confirmed I had not replaced the trigger assembly, then shipped me a hammer.

The hammer came first. I believe it is a MIM part and the original is not. And the 2nd hammer is virtually the same shape as the original. I cannot see that the new one will be any different when it comes to activating the new firing pin safety lever.

So why the new hammer? EDITED: I see that Post # 303 asked the same question, and Post # 340 has answered it.

OBTW, the new hammer was made in India. And India is in the process of a big program to buy new infantry assault rifles. Think there is a connection?

Bart Noir
 
#453 ·
The only difference between the regular BCG and the Geissele BCG is the safety lever. They sent me the regular BCG and then had to send me the "G" marked safety lever. It was easy to change the safety lever.

I think that SIG has been very surprised by the number of Geissele compatible BCGs needed. They gave away free Geissele triggers to anyone that sent in a rifle with a brand "X" aftermarket trigger, then returned the original trigger.

Bill
 
#454 ·
I hope MCX owners have both firing pin lock levers (mil spec and G trigger). I've already switched triggers 3 times (stock -> SSA-e -> ALG -> S3G) and would have been annoyed if I hadn't had both levers. Why so many trigger swaps you ask? I'm the type who keeps changing things until they feel perfect.
 
#456 ·
Not sure if anyone ran into this issue but I received my "upgraded carriage assembly" and made sure it cycled just fine. Put in a magazine it loaded the bullet into the chamber, took it out of safety, but when I pulled the trigger, it just went "click". Bullet was not fired. Pulled the charging handle back, it cycled fine again, ejected my un-fired round and loaded again. I was probably able to fire 2 out of 20 attempts. I even tried other pmags and 3 different types of rounds in .223 and 5.56... [emoji17]


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#457 ·
Not sure if anyone ran into this issue but I received my "upgraded carriage assembly" and made sure it cycled just fine. Put in a magazine it loaded the bullet into the chamber, took it out of safety, but when I pulled the trigger, it just went "click". Bullet was not fired. Pulled the charging handle back, it cycled fine again, ejected my un-fired round and loaded again. I was probably able to fire 2 out of 20 attempts. I even tried other pmags and 3 different types of rounds in .223 and 5.56... [emoji17]
Welcome to Sig Talk! Sounds like your new Carriage Aasembly's firing pin locking lever isn't working with your hammer. These new carriage assemblies come with firing pin locks for either SIG's stock trigger group, or a version that's designed to work with a Giessele trigger.

If these aren't matched up properly, all you'll get is a 'click' with the trigger pull.

Cheers
 
#458 ·
I'm so disappointed in sending my rifle back to Sig Sauer. Yes, I received a upgraded BCG and Trigger. Everything ran fine before I sent it back, but now I have been having trouble with failure to eject. I've put about 400 rounds thru it, and about 15-20 failure to eject. I have had problems with 223 and 556 55 grain ammo. Sometimes it will eject fine, and then it can barely get the spent shell out. I've contacted Customer Service, and I've have sent my rifle back to Sig. Hopefully they can get it fixed. They will probably just change the BCG, and call it good. I really wonder if they really take it out and run any rounds thru it. I will post a update when I get it back from Sig.
 
#461 ·
^^I do wonder if it will ever be worth it as long as you stick to 5.56. I went through an advanced carbine class. Lots of time with my MCX in the dirt--inserting magazines one armed, clearing forced malfunctions one armed, rolling in the dirt and firing. Absolutely no issues with my original Bolt Carrier. So I think I'll just leave well enough alone.
 
#466 ·
Well guess what, I finally got the MCX back from Sig. They told me that they changed out the Gas Block, and put 3 magazines thru it with no problems. Take it out to the range and it started to repeat the same problems just about 12 rounds in the first magazine. I proceeded to change ammo twice, and magazines no difference still FTE after a couple of rounds. Changed shooters, no difference still FTE after a couple of rounds. I've have since sent it back to Sig AGAIN! This is getting old quick. The MCX use to be fun to shoot, but now just a pain in my a##.
 
#469 · (Edited)
I haven't been following this thread for several months now, was waiting for things to settle down a bit.

I have the Cabelas pistol kit, as a matter of fact it's the first serial number in the range that Sig initially put out there for the recall. I SBR'd it shortly after aquisition. My questions are:

1. Has anyone else sent in their kit?
2. Were you satisfied with what Sig did?
3. Did you have to send it back again?
4. Did you change the trigger and what did Sig say about your aftermarket trigger?
5. Was your rifle running fine when you sent it in?
6. Did Sig eliminate the auto regulating gas system?

I bought this rifle because of the auto reg gas and it wasn't DI, spent a lot of money. Have since added the Sig SRD 7.62 Ti direct thread supressor, spent a bunch more money. It runs fine, got rid of the crappy trigger and added a RRA 2 stage. What am I to expect if I send it in? Does anyone have any idea of the turn around time for sending it out to receiving it back? From what I've heard about the kits they want everything sent back and what is sent back to you is about half of the original rifle. That doesn't make me a very happy customer, regardless of the gift card I might receive.

Thanks,
CZU
 
#470 ·
Do you have an extractor o-ring around your extractor spring?

I didn't read this whole thread but noticed it was back on top so I checked this last page. Please excuse me if this o-ring issue has been covered.

I was having extraction problems and noticed upon disassembly for cleaning that the extractor o-ring shown in the manual wasn't there. So I called SIG and asked but was first told the factory doesn't install them anymore. I insisted I wanted one as shown and the rep sent two under the warranty. I put one in and have run several hundred rounds through my MCX without any failures to extract.
 
#471 ·
It's now several months later and Geissele has the new MCX trigger available. Does anyone know if it will fix the (alleged) BCG problems with the original MCXs? Or whether it only works with the upgraded BCGs? I never sent my pistol or carbine in for retrofit because there were so many problems being reported. I also never experienced any issues with my MCX firearms to begin with.
 
#472 · (Edited)
The Geissele trigger should work fine in your unrepentant MCX as Geissele didn't change any hammer geometry. My SSA-E and S3G triggers worked fine in my MCX before I sent my BCG in for the recall. Post-recall, I needed the "G" firing pin lock lever to use those Geissele triggers. With the Super MCX SSA trigger, I went back to the "non-G" lock lever.
 
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