Ive had the gun for a while, and it ran 100% until the last three trips. 2 trips ago, on its first failures, I started to get a couple double-feeds or failure to extract stovepipes. A couple times, the casings would go back behind the ejector and "lock" the bolt to the rear. Failure rate was about 1:15. I was shooting all Federal 100 round packs

The second time, i got a few more of the lock-back hard failures and a few failure to extract the spent shell from the chamber and double feeds. Failure rate was probably about 1 im 10. I tried other ammo, too. American Eagle 124 grain, Federal 100 round packs and even some WWB 115. Malfuctions were consistent with all ammo.

Then yesterday, almost every shot resulted in a failed extraction and a double feed. Most consecutive shots i got off was 2 shots before another failure. I tried 124 and 147 defensive ammos, along with the previously used 124 and 115 grain FMJ So i packed it up and shot other stuff.

I cleaned it like normal after the first failure. I REALLLY cleaned it after the second. Lubed it up a LOT to see if it needed to be shot wet. Still failed worse than ever. I havent cleaned it since yesterday. Is there something i could be doing wrong with it that i could fix or does it need to go to Sig?

Thanks.

This message has been edited. Last edited by: PorterN,

I would check the extractor first, then the recoil system (I'm not familiar with which system the mpx uses).
If you are unsure, call SIG and see what they do (I'm sure they'll fix it).

Do you have the dot on the cam pin toward the dot on the carrier?

Has the chamber and throat been brushed out with some bore solvent?

quote:

Originally posted by Jelly:
Do you have the dot on the cam pin toward the dot on the carrier?

Has the chamber and throat been brushed out with some bore solvent?

The pin is installed correctly. I guess I didn't clean the barrel any more than I typically do - a few wipes of a bore snake.

My first thought would have been to inspect the extractor... but, based on this thread you participated in a few months ago, it seems you may be experiencing similar stoppages, so you might want to start by inspecting the gas valve, extractor spring, and insert. (I'm not sure what "insert" refers to in this post).

2nd Gen MPX feed problems

I figured out the problem. It was a barrel issue - I was using an In-Lead-We-Trust barrel and a quick talk with Rob over there revealed the issue wasnt just mine. I was a VERY earlier purchaser of the ILWT 4" barrel, and theyve been great - it just had a defect in a few of the barrels and mine was one. But Rob has taken care of me 100% since day 1 of the purchase, so im excited to get the replacement barrel and get back to shooting.
A+ grade for Rob and ILWT, though.

Good to hear that you've worked things out. For a while there I was wondering if something bad would befall my 2G MPX.

Didn't think that you'd changed a major component was worth mentioning?

I'll second and probably third that. That omission is just plain annoying to the people who own an MPX reading and following the post. Especially since the last sentence of the original post is "does it need to go to SIG". Nobody in their right mind would write that with a straight face about a gun with a 3rd party barrel. Unless I'm missing something here come on PorterN!! You have been here for awhile.

yep. My fault to omit that detail, and a big one. ya'll are right. It's been in its current 4" configuration with the aftermarket barrel pretty much since I got it (I only went to the range once before getting the new barrel) that it stupidly slipped my mind to think it could be the barrel. I had about 1000 rounds of flawless rounds through it, and hadn't made any changes to it lately, that I immediately worried it was whatever bolt issues I'd seen a few others have in recent months.

TL;DR, i'm an idiot, and Occam's razor wins again, i suppose. aftermarket part breaks first. although, it was an unusual breakage that I definitely WOULDN'T (and didn't) think of first.

So am I to understand a part not made by SIG caused the stoppages? Imagine that. This is why I don't like to tamper with the factory integrity of my firearms or vehicles.

Why would the barrel work for 1K rounds and stop? What changed?

quote:

Originally posted by egregore:
So am I to understand a part not made by SIG caused the stoppages? Imagine that. This is why I don't like to tamper with the factory integrity of my firearms or vehicles.

I get the flak due to my not originally mentioning the aftermarket part, but I'm not sure how an aftermarket barrel in a modular system is different than a third-party trigger job on your CZ.

quote:

Originally posted by 1KPerDay:
Why would the barrel work for 1K rounds and stop? What changed?

Full story: i bought one of the early ILWT 4" barrels. Worked flawlessly til it didnt. I kept trying to clean it to make it work but it got worse. I asked here, and from Gibb mentioning the recoil system and Jelly mentioning the chamber i figured id take the barrel off - at which point i thought - duh. Its aftermarket (as others have said) But again, like you say 1K, why would it suddenly fail? Its a quality barrel, why would that break anyway?? I took the barrel off and there was about a 1cm ring of the barrel around the chamber end that had broken off. Called Rob at ILWT and there had been a recall i missed somewhere along the lines with a few lucky winners of defective first-run barrels (part of the heat-treating process apparently?). I had a good laugh and was glad it was a simple replacement on such a modular design as the MPX. Rob sent me a new barrel as a replacement and I have no doubt ill be back up and running.

Be it a lesson or not for whatever theory or thought yall prescribe to - stay away from aftermarket stuff, dont be a beta tester for new products, reassemble your stuff right, do a field strip or full break down to diagnose problems, etc.

Regardless of the moral yall take from my story, i appreciate the advice of the forum and yalls suggestions that led me to check the barrel. Big thanks to Rob at ILWT for the customer service provided. And ive added it to my list of learning experiences.

This message has been edited. Last edited by: PorterN,

Thanks for the details. Interesting failure point.

I'll give it to you, I would not have thought to check the barrel. I thought one of the advantages of the MPX series was how interchangable it was.

Thanks for the update.

I had a fair bit of failure to feed on my mpx carbine a while back. I was using geco 115 grain ammo. It chrono'd at some wild ass numbers 700-1100 ftps. Once i switched out of geco to a 124 grain it worked flawlessly till it didn't as you put it. The firing pin broke, sig had a new bolt assembly to me in 3 days. Now it even feeds that crappy geco 115grn. Even the poofy rounds from geco. I am convinced there was some sort of drag on the old bolt asembly that caused a delay in the firing pin retracting. Putting the two side by side, i will be damned if i can find it. I might have a failure to feed or extract everyso often, but i have put 6-700 rounds through it with 0 cleaning. SoOOOO, that I think is on me.

quote:

Originally posted by fatmanspencer:
I'll give it to you, I would not have thought to check the barrel. I thought one of the advantages of the MPX series was how interchangable it was.

Yep. Same. I laughed when I took it apart. With the firing pin issues and some people having bolt issues or whatnot, I figured I was in the same boat and poked around a little for their fixes (or what sig fixed for them) before asking for advice here. I guess my thoughts were going that direction anyway so I wasn't assuming a barrel even could be the problem. But I"m glad it was just the barrel, to be honest.