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SIG MPX Failure to Feed from Mag

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5 minutes ago, Excursion12 said:

Has anyone had luck with SIG repairing it?

That's what I'm trying. Do you have the grooves in the receiver races, too?

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Posted (edited)
18 hours ago, DoctorH said:

That's what I'm trying. Do you have the grooves in the receiver races, too?

I had zero luck with Sig:

  • wanted the whole gun shipped on my dime ( over 1 year old)
  • would void any warranty if it had "after market parts" .. i was unwilling to un-pin @ weld the MBX comp and re-pin & weld the stock flash hider back on...
  • stated the expected service life was 25K so I should count my self lucky that I got 30K

I got them to sell me the latest updated carrier, spring gide and buffer and I keep an eye on the ejector to make sure it is not loose again.  the groves line up with the part of the spring guide that dovetails in to the carrier .. 

 

once I went down the over gassed / to fast a powder burn rate + week extractor springs  trouble shooting path all 3 of mine run 100% until the extractor spring wares down ( 7-10K or so) ... and I go 4 times as long  with 50 % less build up on the cleanings 

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Edited by 2011BLDR

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^^ That's crazy, man.

 

I've never heard of that 25k service life before.

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On 7/28/2019 at 8:48 PM, DoctorH said:

That's what I'm trying. Do you have the grooves in the receiver races, too?

Mine doesn't have any receiver damage. Just have that round go vertical into the chamber. Going to try some different profile bullets this week, but not holding out much hope.

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18 hours ago, 2011BLDR said:

I had zero luck with Sig:

  • wanted the whole gun shipped on my dime ( over 1 year old)
  • would void any warranty if it had "after market parts" .. i was unwilling to un-pin @ weld the MBX comp and re-pin & weld the stock flash hider back on...
  • stated the expected service life was 25K so I should count my self lucky that I got 30K

I got them to sell me the latest updated carrier, spring gide and buffer and I keep an eye on the ejector to make sure it is not loose again.  the groves line up with the part of the spring guide that dovetails in to the carrier .. 

 

once I went down the over gassed / to fast a powder burn rate + week extractor springs  trouble shooting path all 3 of mine run 100% until the extractor spring wares down ( 7-10K or so) ... and I go 4 times as long  with 50 % less build up on the cleanings 

 

 

 

So after 25K now what? Buy a new upper? Would they warranty it if you had not changed the parts or would sig say its worn out and make you buy a new one?

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36 minutes ago, Chillywig said:

So after 25K now what? Buy a new upper? Would they warranty it if you had not changed the parts or would sig say its worn out and make you buy a new one?


I'm over 25K suppressed on one of my GMR's. That was back when I was spinning a can on for falling steel and other outlaw matches and spinning a comp back on for USPSA. Keep in mind it was also loaned out with a diet of "I don't care as long as it's 9mm" ammo and "let's run everyone back to back because it speeds up cycle time at the match." 

I guess I'm firmly in the camp of I don't want to spend my time fighting my gear and the manufacturer and just want my guns to run. 🙄

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Posted (edited)

For me based on my military experience with the Colt SMG’s (blow back 9mm) I knew that I wanted a locked breach gun and the advantages it offers. Some key points

·        I was able to replicate the malfunctions in my #2 gun that has none of the gouging in the upper

·        I was able to eliminate the malfunctions in all 3 guns by restricting the gas and beefing up the extractor tension ( same thing you do in an over gassed AR)

·        I believe the loose ejector contributed to the gouging in the upper, combined with the high carrier velocity and the sharp edge on the spring guide dovetail. The new competition carrier and spring guide eliminates this that’s why I bought it for the #1 gun with the gouging in the upper

·        I have seen similar / worse wear issues in other piston systems (SCAR, HK416) that are steel parts in an aluminum receiver. The linear operation of a Direct Impingement AR is really a wonderful thing

·        The hole down the center of the gas plug is critical, as this fouls up with carbon, Bullet coating or lead the volume is reduced and starts the piston moving sooner in the cycle time ( i.e. over gassing)

·        I balance the ammo (155-162 PF) with the gas system, recoil spring rate and comp to get all 3 working together …. Same thing you do with an OPEN gun

·        I could have gotten a new competition MPX when I bought my #3 gun so I could push the #1 gun down to practice/beater status… however based on all my trouble shooting and fixes I felt the last thing the MPX needed was more dwell time ( lounger barrel same gas port location)

Edited by 2011BLDR

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Good news, hopefully: Sig Sauer replaced the upper receiver and BCG. It'll take me a little before I can break them in and see, but let's hope for the best.

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