MPX gas parts - soaking solvent recommendation?

[2011BLDR]

15 minutes ago, SergioSF said:

 

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If I understand the plugs correctly, the small size plugs allow more of the gas to vent out with less obstruction. Perhaps that's enough force/heat to keep 'em cleaner?

 

No, the smaller size plug lets less gas in to the system over a lounger time and restricts the excess flow after unlock.  The piston and plug act as an expansion chamber for the gas when the correct volume is reached the piston moves back creating a larger expansion chamber until the piston passes the vent holes.

[SergioSF]

7 minutes ago, 2011BLDR said:

No, the smaller size plug lets less gas in to the system over a lounger time and restricts the excess flow after unlock.  The piston and plug act as an expansion chamber for the gas when the correct volume is reached the piston moves back creating a larger expansion chamber until the piston passes the vent holes.

 

Aha - thank you!

[zdog]

Soooo.....would you explain what the factory achieved buy going to the open style gas plug please.

 

fwiw.....I recall going through basic training in 1965 and having nothing but problems with the gas system on the M-14.  Glad to see not much has changed.  

[2011BLDR]

16 minutes ago, zdog said:

Soooo.....would you explain what the factory achieved buy going to the open style gas plug please.

 

 

eliminated customer complaints on the system not running on crap ammo  and / or loaded with fast powders ( anything aluminum cased, American Eagle, anything steel cased, WW wight box (exception for 124 NATO wight box load) ). My #1 gun has 30K on it,  my #2 has 18K on it and my #3 has 5K on it... I can induce a malfunction in any one of them by:

• running to big of a gas plug for the ammo velocity/presser/powder burn rate
• letting the expansion chamber area of the gas plug get reduced in volume with carbon/lead build up ( ie early unlock)
• letting the extractor springs get worn out

Running the restricted gas I  can go 2K In between cleanings and have less build up than I used to see on 300 rounds with the open plug's.. 

[zdog]

18 minutes ago, 2011BLDR said:

eliminated customer complaints on the system not running on crap ammo  and / or loaded with fast powders ( anything aluminum cased, American Eagle, anything steel cased, WW wight box (exception for 124 NATO wight box load) ). My #1 gun has 30K on it,  my #2 has 18K on it and my #3 has 5K on it... I can induce a malfunction in any one of them by:

• running to big of a gas plug for the ammo velocity/presser/powder burn rate
• letting the expansion chamber area of the gas plug get reduced in volume with carbon/lead build up ( ie early unlock)
• letting the extractor springs get worn out

Running the restricted gas I  can go 2K In between cleanings and have less build up than I used to see on 300 rounds with the open plug's.. 

 

So I should call Sig and ask for the old style gas plug back they removed and replaced with the open gas plug when it was in for the failure to eject complaint.  Darn.....

 

I feel that the red heavy duty extractor spring and ORing combo was a big step forward.  Was the old style gas plug considered big and was the open gas plug considered small?

 

I only have two MPXs and am waiting for a good excuse to buy a third.

[George16]

50 minutes ago, zdog said:

 

So I should call Sig and ask for the old style gas plug back they removed and replaced with the open gas plug when it was in for the failure to eject complaint.  Darn.....

 

I feel that the red heavy duty extractor spring and ORing combo was a big step forward.  Was the old style gas plug considered big and was the open gas plug considered small?

 

I only have two MPXs and am waiting for a good excuse to buy a third.

 

I went through that a month ago when I sent my gen 2 8” sbr upper. I called them asking to keep the old gas plug but they said no. They installed the new open gas plug that comes with the PCC model and it gets dirty real quick compared to the old gas plug. 

 

So far, everything is running well so that all that matters to me now since I clean my MPX after about 500 rounds anyway.

 

Hindsight is always 20-20 .

[zdog]

4 minutes ago, George16 said:

 

I went through that a month ago when I sent my gen 2 8” sbr upper. I called them asking to keep the old gas plug but they said no. They installed the new open gas plug that comes with the PCC model and it gets dirty real quick compared to the old gas plug. 

 

So far, everything is running well so that all that matters to me now since I clean my MPX after about 500 rounds anyway.

 

Hindsight is always 20-20 .

 

I think you can still buy the old style plug at ILWT.  I’ll try the soaking for a few days to see if that works first.

 

 

[2011BLDR]

10 minutes ago, zdog said:

 

I think you can still buy the old style plug at ILWT.  I’ll try the soaking for a few days to see if that works first.

 

 

Early Gen 2 had the "complex" plug that was replaced with the "open" .. the "open"  ( .114" -.117"  is what I have seen) is the only available part from Sig.. If you want to play with the restricted plugs ILWT is the source .0520" &.0469".

 

My #1 & #2 guns use the .0469" my #3 is a.0520".... BUT I also have the MBX Comp's that increases Back pressure, like a suppressor  and I use speer 115gr TMJ's @ 1400 FPS , federal XM9001 115gr JHP @1425FPS or reloaded 115JHP's @ 1410 FPS.....

Edited June 28, 2019 by 2011BLDR