Stovepipes with MPX, different from other thread

[gunner01]

I have gen 2 MPX carbine, have shot a few thousand rounds of various 115g factory and 115g peak performance remans with virtually no issues.  Have recently installed the Timney MPX trigger and a Raptor charging handle on it and an Isler hand guard.  Otherwise factory standard.  All of a sudden I am getting stovepipes on every mag.  I cleaned the gun including the gas tappet which had a caked on layer of carbon.  I replaced the extractor spring and lubed the bolt carrier group well with oil reassembled the gun.  The stovepipes continued with various ammo and various mags.

 

I swapped the bolt carrier group with my father's new (less than 500 rounds) MPX pistol.  My bolt carrier group ran just fine in his gun (no stovepipes), my gun with his bolt carrier group still stovepipes.

 

Does this seem to indicate a problem with the gas system of my gun???  Clogged gas port?????, bad rings on the tappet?????  Keep in mind this happened quickly one day at a match and the gun went from flawless to stovepipe every mag.

[Archangelgt]

Might be the ejector in your upper receiver. Hit up Rob and In Lead We Trust, he might offer replacements. 

[ck1]

I might try dropping in your old trigger and see what you get? Kind of a long shot, but since the new trigger might be interacting with the bolt differently than your old one, maybe that could be the culprit?

Also, another long shot, but maybe just check the install of your Timney? I know when I pulled the Timney 683 from my PCC model (I prefer a Hiperfire) and installed it in a buddy's Gen 2, we figured out the hard way that Timney's installation directions were wrong, and we needed a different sized hex than what they had stated in order to properly secure the trigger housing correctly with the 2 little screws that press down on the plate (can't remember if it was one size up or down from what they said to use), when it's secure and installed correctly there should be no slop or wiggle in the housing at all...

Edited November 17, 2019 by ck1

[gunner01]

On 11/16/2019 at 8:30 PM, Archangelgt said:

Might be the ejector in your upper receiver. Hit up Rob and In Lead We Trust, he might offer replacements. 

It does not appear to have any damage.

[Nolan]

Are you running the Raptor Charging Handle with or without the new spring plate?  When I installed the spring plate on mine it tipped either the charging handle or the spring guide rods and the bolt would drag.  I took it out and went back to leaf spring I made to hold the charging handle up.

 

Nolan

[gunner01]

On 11/20/2019 at 5:29 PM, Nolan said:

Are you running the Raptor Charging Handle with or without the new spring plate?  When I installed the spring plate on mine it tipped either the charging handle or the spring guide rods and the bolt would drag.  I took it out and went back to leaf spring I made to hold the charging handle up.

 

Nolan

I am using the "support arm" that came with the Raptor.  I assume that is what you mean by "new spring plate" or are there different versions of the Raptor plate?  But, I have been using the raptor with the plate it came with for some time before these stovepipes starting happening.  Also, when I substituted in the bolt carrier group from my father's mpx`it included the factory charging handle and spring plate and recoil springs etc and the stovepipes continued in my gun.  And when I put my group including the Raptor into his mpx it ran without stovepipes.

Edited November 22, 2019 by gunner01

[George16]

Since yours is a gen 2, make sure the dimple on the bolt cam is lined up with the dimple on the bolt carrier. If they’re not lined up, there’s more resistance on the bcg against the chamber as it slides back and forth. It happened to me before. This had been mitigated on the PCC model.

 

Can you post a picture of the bcg showing the orientation of the dimple on the cam bolt?

[gunner01]

4 hours ago, George16 said:

Since yours is a gen 2, make sure the dimple on the bolt cam is lined up with the dimple on the bolt carrier. If they’re not lined up, there’s more resistance on the bcg against the chamber as it slides back and forth. It happened to me before. This had been mitigated on the PCC model.

 

Can you post a picture of the bcg showing the orientation of the dimple on the cam bolt?

Keep in mind, I took my complete bolt carrier group and put it into my father's mpx and it ran fine.  I put his BCG in my MPX and had the same stovepipes.

[2011BLDR]

On 11/16/2019 at 6:51 PM, gunner01 said:

I cleaned the gun including the gas tappet which had a caked on layer of carbon.  

 

I swapped the bolt carrier group with my father's new (less than 500 rounds) MPX pistol.  My bolt carrier group ran just fine in his gun (no stovepipes), my gun with his bolt carrier group still stovepipes.

 

 

Did you also clean the carbon out of the expansion chamber in the gas plug?  as that fills up the piston starts movement sooner, and therefor extraction is started while  the brass is still expanded against the chamber walls causing the extractor to slip off the rim before the case hits the ejector and clears the action..... simple test move the newer gas plug to the problem gun.... an additional consideration is the extractor spring will have been over stressed up to this point and a rebuild would be a good idea...

[George16]

Or buy the extractor spring and o-ring for the PCC model (gen 3) and install it in your MPX.

[gunner01]

3 hours ago, 2011BLDR said:

Did you also clean the carbon out of the expansion chamber in the gas plug?  as that fills up the piston starts movement sooner, and therefor extraction is started while  the brass is still expanded against the chamber walls causing the extractor to slip off the rim before the case hits the ejector and clears the action..... simple test move the newer gas plug to the problem gun.... an additional consideration is the extractor spring will have been over stressed up to this point and a rebuild would be a good idea...

I think you may be on to something.  I think I need to do a better cleaning of the gas system.  As I mentioned above I have replaced the extractor spring and insert and then even tried my father's  bolt carrier group, recoil springs and charging handle in my upper and still got stovepipes.  Today I tried swapping his entire lower with my lower to rule out any trigger component issues mentioned above.  Still got stovepipes.  So really all that is left is a clogged gas system in my upper I think.

[inertia]

Picture of the malfunction?