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Sig MPX FTEject


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Need some help from the collective. 

 

MPX Gen II, upgraded BCG (with fp spring) from Sig (couple of years ago).  I've owned this for a few years and have played with it off and on, but decided this season to go full PCC. Just lately it has really gone down hill, and I cannot pin point reason.

 

Current load is 4.0gr Clean Shot with 125gr RN Blue Bullet at 1.100, PF 143-145.

 

Last two matches were DNFs because it FTExtract so bad, there was no point in going on.  Each time, it would happen 3 or more times per stage.  Each time, I would take same loaded mags, go out back of the house when I got home, and dump the mags with no problems!!  

 

When the FTEject happens, the fired case is still in backwards with the next round or two jammed up under it.

 

I can go to the range and blow through 2-300 rounds with no issues.  Go to a match, and it chokes on me.  No change in my grip, how it's mounted, mags used, etc.

 

Pertinent info:

- Mags are GenII as is the MPX. 1x20,  1x30,  1x34,  2x30s with Springer +10 extensions. Springs appear in good shape.  All mags have been used numerous times during life fire practice with no issues.

- Local match last night it puked on stock 30rnd mag.

- I had been running 3.7 gr CS, it was suggested that maybe not enough gas was being generated, so upped to 4.0 at 143-145 PF.  3.7gr CS was 139-140 PF

- I have 3 sets of "open" gas plugs and tappets from ILWT, that I rotate when cleaned. 

- Gas port is still stock. 

- Piston/tappet is NOT oiled, installed dry. 

- Deep clean (swap plug/tappet) every 750 rounds or so.

- Each deep clean I take a wire and ensue the gas port is clear, and take an old barrel brush to clean out where the piston goes.

- Been running with the SSI billet extractor and extra power spring.  It was suggested the e/p springs are intended when running suppressed. Swapped back to the stock extractor/spring last night, will see how it runs this weekend.

- Match a couple of weekends ago, it DNF on me, I may have had the rotating pin 180 out, causing the pin to hit on the ejector. When I got home from match, pulled it apart to see if anything was wrong (saw marks on round end of pin making me think it may have been 180 out), put it back together, and ran 50 rounds through it with no issues. Yes, I know the dots need to line up.  

- Ejector is not loose, and does not appear to be damaged.

- Recoil springs were replaced with stock weight probably about 2K rounds ago.

- It is possible the Clean Shot is too fast, but it is supposed to be very close to W231 and Sport Pistol, both of which I have used in the past with no issues.

 

I may pick up some OEM 9mm ammo as a test for this weekend's match.  Will update after more testing. TIA

 

 

Choking session last night.

 

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When I had that happened to my gen 2 MPX and sent to sig for repairs, all they did to get it back up running was to install the “gen 3” extractor which has the extra strong spring with a red oring. This was done May last year and I haven’t had any problems since then. 

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13 minutes ago, grsdoug said:

I have heard of issues in some guns with the heavy extractor spring. I run all stock. Other issue could be a loose ejector. How are the matches at Blue Ridge or whatever it is called now?

 

Why I went back to stock extractor & spring.  Will see if that helps.

Ejector is tight.

They are supposed to be better.  There are a couple of good guys involved that are trying to do good.  Will see at the next one.  

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5 hours ago, GregJ said:

 

- I have 3 sets of "open" gas plugs and tappets from ILWT, that I rotate when cleaned. 

- Deep clean (swap plug/tappet) every 750 rounds or so.

 

 

Is the expansion chamber in the gas plug clear? Coated and exposed lead base bullets will fill the expansion chamber in the gas plug causing an over gas issue that results in:

  • early extraction while brass is still expanded in the chamber
  • extractor slips off the case
  • blow back finishes the case extraction but the case never contacts the ejector because it is not on the breach face 
  • faster burn rate powders can add to this issue ( pushing gas in to the gas system early in the dwell time at a faster rate / sooner than a  slower burn rate would have)

in my past experience  the expansion chamber in the gas plug clogged with lead/ polymer coating is extremity difficult to clean out even with metal scraping tools.  I gave up on one after 3 hours of work and only 20% progress against the lead fouling, I replaced it and threw it in the trash, I only shoot JHP or TMJ now  with CFE or Sport pistol and bought a good Ultrasonic tank.

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2 hours ago, 2011BLDR said:

Is the expansion chamber in the gas plug clear? Coated and exposed lead base bullets will fill the expansion chamber in the gas plug causing an over gas issue that results in:

  • early extraction while brass is still expanded in the chamber
  • extractor slips off the case
  • blow back finishes the case extraction but the case never contacts the ejector because it is not on the breach face 
  • faster burn rate powders can add to this issue ( pushing gas in to the gas system early in the dwell time at a faster rate / sooner than a  slower burn rate would have)

in my past experience  the expansion chamber in the gas plug clogged with lead/ polymer coating is extremity difficult to clean out even with metal scraping tools.  I gave up on one after 3 hours of work and only 20% progress against the lead fouling, I replaced it and threw it in the trash, I only shoot JHP or TMJ now  with CFE or Sport pistol and bought a good Ultrasonic tank.

Yes.  I soak the plug and tappet in kerosene for several days, then run them in an u/s cleaner for an hour or two.  After taking out of the u/s I make sure rings turn freely, and the chamber in the plug is clear.

 

EDIT: @2011BLDR I think you are probably spot on.  I thought I had been cleaning the expansion chamber out enough, but apparently I have not been paying close enough attention to it.  Below are a couple of pics of cleaning a plug out, that I believe had been giving me the most issues.  When I started, the pick went halfway down the chamber.  Adding gas (higher powder charge) to this shortened chamber, would have exacerbated the problem.  Correct?  

 

Thanks very much!   :cheers:

IMG_1405.JPG

Edited by GregJ
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20 hours ago, GregJ said:

Yes.  I soak the plug and tappet in kerosene for several days, then run them in an u/s cleaner for an hour or two.  After taking out of the u/s I make sure rings turn freely, and the chamber in the plug is clear.

 

EDIT: @2011BLDR I think you are probably spot on.  I thought I had been cleaning the expansion chamber out enough, but apparently I have not been paying close enough attention to it.  Below are a couple of pics of cleaning a plug out, that I believe had been giving me the most issues.  When I started, the pick went halfway down the chamber.  Adding gas (higher powder charge) to this shortened chamber, would have exacerbated the problem.  Correct?  

 

Thanks very much!   :cheers:

IMG_1405.JPG

Yes the exact thing I was explaining.... as the expansion chamber fills up the time to start piston movement and the unlock/extraction process starts sooner = extraction while the case is still expanded against the chamber =  case comes off the extractor/ breach face but doesn't hit the ejector. 

 

With 3 MPX's and 60K rounds down range I am  convinced this is the key element in MPX reliability issues... 

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7 hours ago, 2011BLDR said:

Yes the exact thing I was explaining.... as the expansion chamber fills up the time to start piston movement and the unlock/extraction process starts sooner = extraction while the case is still expanded against the chamber =  case comes off the extractor/ breach face but doesn't hit the ejector. 

 

With 3 MPX's and 60K rounds down range I am  convinced this is the key element in MPX reliability issues... 

 

I agree.  However I just came back from the range, rounds with 3.7 gr Clean Shot with 125gr Blue, it was a single shot for the first 4-5 rounds, had to rack bolt to chamber next round.  4.0 gr CS same bullet had usual FTExtract jams.  The piston exp chamber is absolutely clean.  Now it seems like maybe the gas port is partially clogged?!?!?

 

I have some factory ammo I plan to see how it runs with (Winchester, WWB, and PMC) that I've had stashed away.  If it runs ok with these, then it's time to work up a new load. Maybe CS is just too fast a powder?  The last hand loads I recall that I ran consistently in it were 124gr Zeros with W231.  

 

Oh, and I have a new MPX PCC on the way from Sig, but I need to get this one squared away.   TIA

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@2011BLDR I think I have verified what is going on, the Clean Shot just does not generate enough gas, even though PF is about 143-145, which unto itself is very interesting.

 

I tried the single round in mag test to see if it would lock the bolt open. My 3.7gr and 4.0gr of CS did not lock the mag back using a good 30 rnd mag.  I then did the same with PMC, Winchester, and WWB, and all 3 locked the bolt back.

 

I then ran about 40 rounds of PMC and Winchester with no issues. I ran about 15 rounds of my 4.0 CS thru, and it jammed on the 12th round, with the empty case sticking out of the chamber. Enough proof right here!!!

 

Another interesting item, the ejected brass from my CS loads were about 6-8' away, where the factory ammo was 12-14' away!! Further proof the CS isnt producing enough gas.

 

I have some Everglades 124 plated and Shooters World Auto Pistol (supposed to be close to N340) on the way.  This combo should easily produce the gas needed.

 

Thanks!!!!  :cheers:

 

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I ran about 8lbs of N340 I had leftover  from my limited days..3N37 is to hot melts the gas rings on the plug fairly quickly no presser signs just to much heat at the gas block... CFE Pistol has been my go to latley but out of stock with the panic so moving to sport pistol

Edited by 2011BLDR
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The cases that were ejecting were not going very far from the gun. When the load/PF is correct and gun clean and functioning the empties should be going 10+ feet away from you and forward of the ejection port. 2 feet and backwards something is slowing the bolt down - dirty, low PF, recoil spring too strong, something

 

What was that gawd awful sound in the background - donkeys? 

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3 hours ago, GregJ said:

@2011BLDR I think I have verified what is going on, the Clean Shot just does not generate enough gas, even though PF is about 143-145, which unto itself is very interesting.

 

I tried the single round in mag test to see if it would lock the bolt open. My 3.7gr and 4.0gr of CS did not lock the mag back using a good 30 rnd mag.  I then did the same with PMC, Winchester, and WWB, and all 3 locked the bolt back.

 

I then ran about 40 rounds of PMC and Winchester with no issues. I ran about 15 rounds of my 4.0 CS thru, and it jammed on the 12th round, with the empty case sticking out of the chamber. Enough proof right here!!!

 

Another interesting item, the ejected brass from my CS loads were about 6-8' away, where the factory ammo was 12-14' away!! Further proof the CS isnt producing enough gas.

 

I have some Everglades 124 plated and Shooters World Auto Pistol (supposed to be close to N340) on the way.  This combo should easily produce the gas needed.

 

Thanks!!!!  :cheers:

 

Or your still shooting coated bullets through a gas gun. At some point you will find enough powder to overcome this by powering the coating through the gas system but that's not a real solution. My gen 2 runs 100% with 3.5g of n320 which is sub minor but a 125g jacketed bullet, my 3rd gen will run with even less. Try a different powder yes but you dont need open gun gas to run this gun. I got 3.1 of n310 to run but didn't like the pressure signs so stuck with 320.

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22 hours ago, Chillywig said:

The cases that were ejecting were not going very far from the gun. When the load/PF is correct and gun clean and functioning the empties should be going 10+ feet away from you and forward of the ejection port. 2 feet and backwards something is slowing the bolt down - dirty, low PF, recoil spring too strong, something

 

What was that gawd awful sound in the background - donkeys? 

 

My pistol handloads have a PF of 143-145 in the MPX, yet they cases dropped 6-8 ft away at approx 2 o'clock.  I am very anal about cleaning my guns.  I really think the Clean Shot is not producing enough gas, but will test more soon and see.

 

LOL, that was the bullet catcher, it's like a belt that takes all the projectiles away to a collection point.  Gets a little noisy at times.

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21 hours ago, inertia said:

Or your still shooting coated bullets through a gas gun. At some point you will find enough powder to overcome this by powering the coating through the gas system but that's not a real solution. My gen 2 runs 100% with 3.5g of n320 which is sub minor but a 125g jacketed bullet, my 3rd gen will run with even less. Try a different powder yes but you dont need open gun gas to run this gun. I got 3.1 of n310 to run but didn't like the pressure signs so stuck with 320.

 

From my research here, a LOT of guys are running coated bullets in their MPX.  Maybe they have just been lucky.  Anyway, I will have some plated bullets and new powder to test. The new powder is not an open powder, just a little slower, comparable to N340.   I can easily load some plated with my current load and see how/if it functions better.   :cheers:

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I was running 115grn blues and had constant fte issues. I had a gm pcc shooter tell me to give up on the coated as they will cause feed issues. After 2 months of continuing to try to get the blues to work I gave up and went with berry plated bullets.
The problem went away after changing over. The only time I have issues now is if I fail to keep the gas system clean and the bolt well lubed.

Sent from my LM-G820 using Tapatalk

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8 minutes ago, mstamper said:

I was running 115grn blues and had constant fte issues. I had a gm pcc shooter tell me to give up on the coated as they will cause feed issues. After 2 months of continuing to try to get the blues to work I gave up and went with berry plated bullets.
The problem went away after changing over. The only time I have issues now is if I fail to keep the gas system clean and the bolt well lubed.

Sent from my LM-G820 using Tapatalk
 

 

It happens. Some guns just prefer the geometry or surfaces of only certain bullets and COL's

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9 hours ago, Glockster1 said:

 

It happens. Some guns just prefer the geometry or surfaces of only certain bullets and COL's

Um or, and I know this is a crazy idea, you shouldn't shoot coated bullets through a mpx, cause it's a gas gun with a gas port in the barrel.

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I'll chime in. I've been running a Gen 2 MPX for over 3 years with nothing but plated 124 Rainier RN bullets & HS-6 powder.  The only problems I've experienced were when I first bought my TTI extensions they were not shipping with XP springs and I was trying to use the factory 30 round springs.  New XP springs fixed my Fail to Feed issues, and the gun has been running well ever since.  

 

Initially I thought a slower powder like HS6 with a good comp. was key to keeping the muzzle down. I blame 15+ years of shooting Open on that theory.  But I recently tried shooting some TG loads that i worked up for my CO guns and the difference was amazing.  I've only run about 100 rounds of that TG load through my MPX now but I plan on trying more of that very soon. 

 

So GregJ, the bottom line here is I'm not really sure if the Power Factor or the amount of gas is as much your issue as is the type of bullets you are using.  Plated bullets have worked just fine for me.

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I fought the failure to eject problem for quite awhile on my gen 2. I checked and fooled with all the things you are looking at. The problem was that my load was too light.  I bumped my powder up to the limit and life was good. I am shooting 147gr FMJs over 3.4 of Universal.

Edited by zdog
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