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Sig MPX gas port


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My 8" Gen 2 would not cycle my pistol Minor PF load (which is 3.2 gr of 320 under a 135 gr RN Bayou Bullet). Sent the barrel off to Taylor who opened up the port to .060" and re-threaded the barrel to 1/2x28 while he had it. Now runs the pistol load like a top, about 1.5K rounds so far and no issues. Locks back the bolt using short mags but not reliably with the Springer 40 rd extensions, but pretty sure this is a mag spring issue, not the gun.

 

I have not chronoed this load in the MPX and could probably build it softer but it has very low recoil, runs reliably and I like having one batch of 9mm match ammo to deal with......

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My understanding is that the gas port is .005 smaller on the Gen 2 and folks were wanting the port to be back the Gen 1 size.   My barrel is only 8".  Not really sure what people are considering low PF loads for the MPX either?  Never used AutoComp before but got enough to make 50 rds or so ... I'd be just s happy to stay with WST.  Been using it for years and love it.  The very few rds I put through my MPX with WST felt nice and I have a ton of it ....

 

 

+1, I've sent an email also with no response, haven't tried calling yet.  Would really like to get my gas port to him ....

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On 2/27/2017 at 7:16 AM, surgdog said:

Sumtoc, how did you get in touch with Taylor? I have emailed and tried to call to no avail. I want to send mine to him as well. Just don't know how.

 

Thanks,

 

mk

 

Sorry for the late reply. Found Taylor on the MPX FB Group, he's a member and you can find his info there.

 

Some good info in the group but many members do not shoot matches so don't have some of the concerns we have.........

 

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  • 3 weeks later...

Well after several attempts to get in touch with Taylor--the last time I thing they picked the phone up and hung up I found ZR Tactical Solutions. They promptly answered an email so I'm going to send my barrel and gas port to them to enlarge the gas port. They have it listed as a service on their site for $75,

 

I guess Taylor has more business than he can handle to not even reply but good for him.

 

ZR states they have a 2-3 day turn around. I'll let you know.

 

 

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On 1/25/2017 at 0:24 PM, 2011BLDR said:

The MPX is a gas system it needs gas pressure  and dwell time to function. For a Gen 2 gun you just need to pick your powders from the correct burn rate category  (N340, HS6, WSF) . Don't try to use a small charge of fast powder like in a production minor pistol it will not generate  either gas pressure  or dwell time in to the operating system.. 

 

This is interesting.  I've had some instances of bulged brass from my Gen 2 MPX carbine using my 9 minor loads (3.6gr E3, 124gr Zero). I dont recall ever seeing this with factory ammo.  I've often thought of trying a slower powder in the MPX, though I have never had a problem with it cycling.  I did call Sig about the bulged brass, and they sent me an upgraded BCG for it (carrier, firing pin, and new fp spring, that the G2 no longer has from the factory), which didnt seem to help a lot.  I will load some WST up and see how it runs. 

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1 hour ago, GregJ said:

 

This is interesting.  I've had some instances of bulged brass from my Gen 2 MPX carbine using my 9 minor loads (3.6gr E3, 124gr Zero). I dont recall ever seeing this with factory ammo.  I've often thought of trying a slower powder in the MPX, though I have never had a problem with it cycling.  I did call Sig about the bulged brass, and they sent me an upgraded BCG for it (carrier, firing pin, and new fp spring, that the G2 no longer has from the factory), which didnt seem to help a lot.  I will load some WST up and see how it runs. 

Greg, have you chronoed your E3 load in the MPX?  My pistol E3 load was 160pf in my MPX.  It would not run when I dropped the charge weight down to get to 133PF.  Still, pretty damned soft at 160pf though. 

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On 2/28/2017 at 10:33 PM, Nimitz said:

My understanding is that the gas port is .005 smaller on the Gen 2 and folks were wanting the port to be back the Gen 1 size.   My barrel is only 8".  Not really sure what people are considering low PF loads for the MPX either?  Never used AutoComp before but got enough to make 50 rds or so ... I'd be just s happy to stay with WST.  Been using it for years and love it.  The very few rds I put through my MPX with WST felt nice and I have a ton of it ....

 

 

+1, I've sent an email also with no response, haven't tried calling yet.  Would really like to get my gas port to him ....

My current load for my MPX carbine is 4.8gr of Autocomp pushing 124gr pills. The only load I found to be softer was with 4gr Titegroup pushing the same bullets. I'm just doing Autocomp right now to use up the reminder one pounder. This is after 2k rounds of trials with different bullet weights and powder combinations. I found that my MPX likes 124 and it is the softest shooting from all other type of bullets. 

 

This is my opinion and someone educate me if I'm wrong. We know 9mm doesn't have a lot of recoil so muzzle rise is mostly from the bolt movement. So the way I see it is to get the bolt back in battery as soon as possible so it would cancel out muzzle rise. So I don't focus on making the softest loads just what gives me the less dot bounce. If that requires me to make 170pf ammo, be it. 

Edited by MrRick
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5 hours ago, Neomet said:

Greg, have you chronoed your E3 load in the MPX?  My pistol E3 load was 160pf in my MPX.  It would not run when I dropped the charge weight down to get to 133PF.  Still, pretty damned soft at 160pf though. 

 

Yes I did. The E3 chrono'd about 134 out of the MPX. Which was surprising that I still wound up with bulged brass.  Now in full disclosure, I had just gotten my 1050 w/AmmoBot and was getting it dialed in, so that may have been a factor as well.  I intend to play with it some this weekend again with some loads with A#2 and see what happens.  --Linky--

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I am trying Bayou 105s with 3.7-3.8 of TG, haven't chroned yet but a friend is shooting the same load and he is easily making 130pf. Very soft shoooting not quite as soft as 148gr Bayou's under 3.2 of N320, but I prefer the faster cycling of the 105 load the dot seems to settle much more quickly. I have never loaded a 9mm so short, 1.05 oal but it has feed without an issue so far. 

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Don't know how many of you know this but apparently Sig went away with the bleeder valve (gas valve) and went to a solid plug. Wonder what benefits it has over the original one. Tempted to order one or modify my extra one to see if I can mess with softer loads. 

IMG_2306.JPG

IMG_2307.JPG

Edited by MrRick
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Don't know how many of you know this but apparently Sig went away with the bleeder valve (gas valve) and went to a solid plug. Wonder what benefits it has over the original one. Tempted to order one or modify my extra one to see if I can mess with softer loads. 


Time to call SIG tomorrow and see what this is all about.
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36 minutes ago, IntenseImage said:

 


Doubt they will respond ... Hell I'm not sure calling will help but at least I can bug the shit out of them

 

I have a pretty contact there. He has been helpful when my valve fell apart and when I needed a new hammer ( lost original). 

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This is what Sig said about the new plug. 

 

"Rick,
The original self-regulating valve works well. It was made specifically with a bigger gas port to function with a very wide variety of ammos(lower quality to high end). The new plug does require SAAMI spec/NATO spec quality ammo. Undercharged or cheaper ammo may have some cycling issues. The plug is passive where the SRV was a little more complex and would dump excess gas, improving durability of the firearm while still allowing it to cycle lower ammo. The plug does not dump gas but runs slightly slower which provides longevity on the parts like the valve did but requires better ammo. The good news is they are interchangeable and the plug should be available for order soon if you want to go that route."

 

I would figure the new plug would be work backwards. I guess the MPX coming with the plug have a smaller gas port. 

Edited by MrRick
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On 3/31/2017 at 10:27 AM, MrRick said:

I would figure the new plug would be work backwards. I guess the MPX coming with the plug have a smaller gas port. 

 

Yeah that makes sense to me too, like it would help cycle softer loads. 

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I sent my barrel and gas block to ZR Tactical this past Monday for port enlargement and got it back Saturday, less than a week!!!! Nice, responsive company with incredible turn around. They even loosen the flash hider for me since I couldn't get it to budge. If their gas port enhancement works as well as their service I should be set.

 

Will give a report when I get a chance to get to the range.

 

mk

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On 3/31/2017 at 1:27 PM, MrRick said:

This is what Sig said about the new plug. 

 

"Rick,
The original self-regulating valve works well. It was made specifically with a bigger gas port to function with a very wide variety of ammos(lower quality to high end). The new plug does require SAAMI spec/NATO spec quality ammo. Undercharged or cheaper ammo may have some cycling issues. The plug is passive where the SRV was a little more complex and would dump excess gas, improving durability of the firearm while still allowing it to cycle lower ammo. The plug does not dump gas but runs slightly slower which provides longevity on the parts like the valve did but requires better ammo. The good news is they are interchangeable and the plug should be available for order soon if you want to go that route."

 

I would figure the new plug would be work backwards. I guess the MPX coming with the plug have a smaller gas port. 

 

I tried all low quality ammo I can find in my carbine, they all worked fine, so.... am i the lucky one? lol

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3 minutes ago, chopinlover said:

I tried all low quality ammo I can find in my carbine, they all worked fine, so.... am i the lucky one? lol

They only ammo that doesn't run in my MPX is 3.2grs of TG pushing 147 pills. Everything that I have gotten off the shelf has ran and I mean everything. About 2000 rounds of random brands and bullet weights. My favorite off the shelf ammo is BBM 115gr. 

Edited by MrRick
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