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mikey_golds

MPX Gen2 or 3 Advice

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Hey guys,

 

Just wondering are there any major differences between the Gen2s vs the Gen3(PCCs).

 

Found a local on GB https://www.gunbroker.com/item/825705093 its a Gen 2 but comes with a few extras, vs buying a new Gen3PCC

 

Figured Id get some more concise advice from here vs googling my face off

 

Thanks in advance

MG

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1 hour ago, mikey_golds said:

Hey guys,

 

Just wondering are there any major differences between the Gen2s vs the Gen3(PCCs).

 

Found a local on GB https://www.gunbroker.com/item/825705093 its a Gen 2 but comes with a few extras, vs buying a new Gen3PCC

 

Figured Id get some more concise advice from here vs googling my face off

 

Thanks in advance

MG

Seems that gen 3 has much less problems... no-brainer for me.

 

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I have both.  Get the new version.  Definitely.  Sig appears to have really addressed the reliability issues through a multitude of changes in this model.  

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2 hours ago, Neomet said:

I have both.  Get the new version.  Definitely.  Sig appears to have really addressed the reliability issues through a multitude of changes in this model.  

 

thanks for the feedback. that where I am leaning the mags were the big thing on this. Was going to go budget build a foxtrot mike or QC build with a BA barrel but at the end of the day I am what  100-150 less then just going MPX PCC, best price I have seen is 1512.99

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1 hour ago, mikey_golds said:

 

thanks for the feedback. that where I am leaning the mags were the big thing on this. Was going to go budget build a foxtrot mike or QC build with a BA barrel but at the end of the day I am what  100-150 less then just going MPX PCC, best price I have seen is 1512.99

 

My pleasure.  That is a good price by the way.

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On 8/10/2019 at 5:04 PM, Neomet said:

I have both.  Get the new version.  Definitely.  Sig appears to have really addressed the reliability issues through a multitude of changes in this model.  

 

Such as?

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3 hours ago, Bifurcate said:

 

Such as?

 

Totally new carrier design to eliminate tilt (thus less energy req'd to cycle) gas port sizing, etc.

 

 

Gen 1 pistol or Gen 3/PCC at this point. 

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3 minutes ago, Acer2428 said:

 

Totally new carrier design to eliminate tilt (thus less energy req'd to cycle) gas port sizing, etc.

 

 

Gen 1 pistol or Gen 3/PCC at this point. 

 

So did they massively reduce the peak bolt velocity or overall cyclic rate down from 1100 actual (850 claimed)?


OR did they just increase the size of the operating window?

 

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Does the new bolt carrier design retro fit to older guns?

 

Nolan

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8 hours ago, Nolan said:

Does the new bolt carrier design retro fit to older guns?

 

Nolan

Yes... I have the newest carrier, spring guide  and buffer in my oldest gun.

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I would say get a Gen 3 but if you can get a Gen 2 with a gas port opened, that's fine to.  I have a lot of trigger time on both and here are some observations:

-The Gen 3 port is a little larger than the Gen 2 port but still fairly restricted - if you run 147 grains at PF you may have issues.  

-The Gen 2 has a pinned and wielded comp that gives a total 16"; the Gen 3 has a 16" barrel and a relatively worthless comp past that - you'll notice that small difference in tight shooting situations; best is taking a Gen 2 barrel, removing the birdcage, and putting a 'real' comp on.  From that I've experienced with 'real' comps on AR 9mms, if you run 124s or 115s with medium burning powder, the comp is doing something.  You can really see the gas in videos - its difficult for me to comment on exactly how much the gas is doing compared to an Open 2011.  

-Both the Gen 2 and Gen 3 barrels seem to have the same accuracy - with 147s and fast powder you can get 1" groups - if you run faster bullets like 124s you can get everything touching at 20 yds.

-A lot of things can be retrofit from a Gen 3 to a Gen 2.  I sent my Gen 2 to SIG and they sent it back with the updated bolt carrier group.  The extractor spring/insert/and Oring are different on the Gen 3 but can be fit on a Gen 2, just like the actual firing pin spring.  Gooseneck and bolt carrier are completely different with the Gen 3 but can work on a Gen 2.

-One part that is not the same is the piece that holds the springs on the recoil rods - don't know the official title.  The Gen 3 has a small cut out in the frame and a corresponding bit of metal on that end piece - the Gen 2 does not.  And so a Gen 2 end cap works in a Gen 3 lower but not vice versa.

-The rubber buffer that the bolt slams in to is also different on the Gen 2 than the Gen 3.  Of note, don't waste your money on the TACCOM buffer + wave spring.

-The Gen 3 comes with the Timney trigger which was halfway decent at a 4lbs kind of clean break.  Its good enough for a backup but throw a Hiperfire in there and call it a day.  I ran an older Hiperfire flat trigger and now have a Eclipse curved trigger - change your Hiperfire springs out once a year - mine broke at a major match.

 

Let me know if you have questions - I've spent way more time tinkering with MPXs that I ever would have imagined.  

 

 

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8 hours ago, rpm8300 said:

-The Gen 3 comes with the Timney trigger which was halfway decent at a 4lbs kind of clean break.  Its good enough for a backup but throw a Hiperfire in there and call it a day.  I ran an older Hiperfire flat trigger and now have a Eclipse curved trigger - change your Hiperfire springs out once a year - mine broke at a major match.

 

 

My Gen 2 MPX with a Hiperfire 24C killed the disconnector spring in about 2500 rounds.  The disconnector would not release the hammer until I pushed the trigger forward.  When I took the trigger apart, the disconnector spring was smashed and distorted.  I replaced it with a standard AR disconnector spring and it killed it in about 500 rounds.  Right now I'm experimenting with a polymer insert in an AR disconnector spring similar to the insert in the extractor spring.  So far, so good, but I've only got a couple hundred rounds on it.

 

Nolan

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Posted (edited)

I had a Gen 1 that was terrible, and have witnessed a few Gen 2’s have issues enough so to stay away... because maybe I’m a masochist, I recently picked up a Gen 3 PCC... so far through about a 1000rds it runs perfectly... I pulled the Timney and dropped in a Hiperfire 243G/Reflex, from what others are saying I’ll just plan on changing out the disconnector spring a couple times a year to keep the trigger humming along hopefully...

Gen 3 seems noticeably better though so far.... going back and forth between MPX and blowback, the MPX just spoils you when it runs, recoils like an airsoft or some toy nerf gun, as long as it runs lol 🤪

Edited by ck1

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Pros and Cons - MPX is way softer, but dot settle time is slower and its inherently LESS reliable than a blowback AR.  AR, even with the softest load and buffer aftermarket junk, will never feel like an MPX - with the right load the dot will recycle faster.  

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On 8/19/2019 at 7:08 PM, rpm8300 said:

Pros and Cons - MPX is way softer, but dot settle time is slower and its inherently LESS reliable than a blowback AR.  AR, even with the softest load and buffer aftermarket junk, will never feel like an MPX - with the right load the dot will recycle faster.  

 

:D

 

You should try the CMMG.

 

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Hey all, not an expert here just a new MPX G3 PCC owner wondering if I can tap into your know-how.  TLDR; will chopping ~9" off the barrel affect reliability?  

 

Longer version: I love the MPX PCC... shooting it is like cheating.  But my daughter finds it too heavy on the front end to shoot for long, and that's the main reason I bought it, for her to shoot (haha that's what I told myself anyway).  So I'm looking at a SBR chop on it, to reduce the weight and if I want to, throw my Osprey 9 on the front.  I just don't want to mess with the reliability - the reason I went with the G3 - cuz I'm not expert enough to troubleshoot cycling issues on the MPX.

 

Thank you folks,
Nathan 

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