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View Full Version : Sig Sauer MPX-9 Gen 2



Buckaroobonsai
01-28-2018, 21:32
Picked it up yesterday and took it out today. Ran some 300 rounds through it. Here’s my two cents.

Design:

Overall great design. Looks like it means business. Love the way the handguard and barrel easily swap out. Same with the stock. I’m new to keymod and totally dig it. Magazines. Translucent so you can see if there’s any ammo left I’m guessing but not so useful for the last handful of rounds which disappear into the magazine well anyways. Otherwise they look kinda funky. Hopefully Magpul gets onboard with that and other parts soon. The flared mag well kicks ass though. Pistol grip. Feels too big for the gun and sits at a weird angle. The standard folding pistol brace gets the job done but looks fugly.

Function:

Capable of nice tight groups at 25 yards. Torso sized targets at 100 yards is do able as well. Charging handle is Ambi but you really need to pull both sides at the same time for smoother operation. LRBHO. Awesome. Works well and a nice tactical advantage over the MP5. Trigger. A little gritty, typical heavy milspec pull but reset is nice and short. Feels like I’ve been doing trigger finger push ups after that many rounds and I could notice it affecting my accuracy as the day went on.

Reliability:

Ran Ranger duty ammo and white box Winchester flawlessly. Don’t know if was because it was getting dirty, but I had a couple double feed failures using LAX Ammo reloads. Maybe a combination of two...

Serviceability:

Easy to break down and clean. The bolt is like a mini AR BCG with (2) guide springs. Mostly proprietary parts of course, but everything looks user friendly for replacement.

Upgrades:

Ordered the Sig collapsible pistol brace to replace the folding one. Looks and functions like the SBR stock but with a brace at the end. Better functionality and hella better looking. Might stamp it later in life and throw a regular collapsible stock on it. A can is tempting too. The factory trigger had to go. Installed a Geissele G2 in less than (5) minutes. Same with the pistol grip, Magpul MOE to the rescue and it feels so much better now. Heard you could swap charging handles but that’s not the case. The stock one is shorter and slightly different at the end. No Gunfighter love for now. Topped it off with an EoTech XPS2 for quicker target acquisition.

Conclusion:

I wanted something that used the same ammo as my Glock 17. Due to the price I looked into an AR-9 first, especially one that could use Glock mags. Ultimately I went with the MPX for the reliability with different types of ammo and it’s purpose specific design. It’s pricey yes, especially with the upgrades, but you know what they say, “cry once”.


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The collapsible Sig pistol brace:

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To Bear Arms
01-29-2018, 06:50
I have swapped out the same parts you did. I am running a Franklin trigger for now and love it. I also did not like the charging handle and just swapped it out for a Radian Raptor charging handle. The Radian takes care of the slop that the factory handle has.

drew890
01-29-2018, 08:29
I’ve enjoyed mine.
It now wears an Aimpoint T2 as well.
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Buckaroobonsai
01-29-2018, 16:34
Nice! You guys have any issues running aftermarket triggers in them? I’ve heard they may be prone to getting damaged? Any other manufacturers making accessory parts for them? Where’d you get the MP5 style sights drew?

drew890
01-29-2018, 16:59
My aftermarket trigger only has about 1,000 rounds through it, but it is not showing any signs of abnormal wear.
The HK sights are a Centurian set that I had on another less used upper.

Buckaroobonsai
01-29-2018, 17:43
Did you need to re-install the wierd “bridge” part that was attached to the factory trigger?

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drew890
01-29-2018, 18:40
Did you need to re-install the wierd “bridge” part that was attached to the factory trigger?

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I did not bother to.

Delfuego
01-29-2018, 18:54
Who is this member "Buckaroobonsai"? He seems very familiar...

Buckaroobonsai
01-29-2018, 20:12
Who is this member "Buckaroobonsai"? He seems very familiar...

Never heard of the bum...

Buckaroobonsai
01-31-2018, 19:29
Added the Sig (3) position brace and a Magpul Rail Light with Streamlight PolyTac.

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Buckaroobonsai
02-04-2018, 17:54
Ran it outdoors today in 16°F. About 300 flawless rounds with a can to boot. Was wondering about the eotech since I zeroed it at 50°F but I didn’t notice any significant change in zero hitting steel at 25 and 50 yards, no problem.

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Buckaroobonsai
02-10-2018, 15:10
Have you guys found any good tac light options for the MPX? There’s not much room on the handguard...

drew890
02-10-2018, 15:49
Have you guys found any good tac light options for the MPX? There’s not much room on the handguard...
Slightly older pic, currently run a Surefire x300 on a 10 o’clock mount.
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Buckaroobonsai
02-10-2018, 15:59
Oh nice. What’s opposite it, a laser?

drew890
02-10-2018, 18:28
Oh nice. What’s opposite it, a laser?
Yup, a Steiner. It currently has an Aimpoint T2 on it; these pics are a little old.
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Buckaroobonsai
03-05-2018, 19:29
Settled on a Streamlight ProTac and Romeo 4H instead of the bigger Eotech.
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lostcolorado
03-07-2018, 19:21
Timney triggers single and 2stage, curved and straight.

https://www.timneytriggers.com/shop/sig-replacement-triggers.aspx

Buckaroobonsai
03-18-2018, 17:59
Yeah those look pretty cool. Trying out these JP springs with the factory trigger first before dropping that kind of money on a new one. So far I’m pretty impressed!

https://www.jprifles.com/buy.php?item=JPS3.5T

izzy
03-19-2018, 12:02
This reminds me. I'm looking for a 3 lug adaptor for my new MPX upper. Anyone have an extra? Most of my typical go to stores online are sold out of them.

Buckaroobonsai
03-21-2018, 21:01
This reminds me. I'm looking for a 3 lug adaptor for my new MPX upper. Anyone have an extra? Most of my typical go to stores online are sold out of them.

Don’t have an extra, but here they are in stock:

https://www.gunbroker.com/item/754093448

izzy
03-21-2018, 21:48
Don’t have an extra, but here they are in stock:

https://www.gunbroker.com/item/754093448

Why did I not think to look on gunbroker? [facepalm]

Buckaroobonsai
03-30-2018, 19:51
Picked one up from gunbroker. Looks to be good quality.

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Buckaroobonsai
08-09-2018, 21:11
Finally got my stamp. Oh yeah, that’s MUCH better...

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izzy
08-09-2018, 21:21
Nice! I wish I could get a picture that nice of mine.

izzy
08-09-2018, 21:39
The siblings. 9mm and 300blk. I'm pretty happy with the brace, don't even think I'm going to SBR the 2nd one. I do prefer the folding stock to the collapsable one however so who knows.

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MattR
08-10-2018, 20:03
I've been kicking around getting a Rattler, how do you like it? I also saw they have an MPX-K Tacops now, it looks pretty cool.

izzy
08-11-2018, 10:25
I've been kicking around getting a Rattler, how do you like it? I also saw they have an MPX-K Tacops now, it looks pretty cool.

I really like the rattler, it's all I've been shooting lately. It's a little funky to take the bolt apart for cleaning but not too bad. Now that I have my loads perfected I can crank out subs for it too. PM me if you want to try it out sometime.

Buckaroobonsai
09-06-2018, 16:24
My shorty just got shorter.

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Hoser
09-06-2018, 18:34
Thats really fucking cool.

00tec
09-06-2018, 18:37
My shorty just got shorter.

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Jesus that's tiny. Do you just velcro that thing to the ticket book or what?

Buckaroobonsai
09-07-2018, 06:40
Jesus that's tiny. Do you just velcro that thing to the ticket book or what?

Nah, I just clip it to the carabiner on my car keys.

:D

Skywalker
02-09-2019, 09:06
Beautiful gun and very nice upgrades. Enjoy!

FireMoth
02-26-2019, 04:03
Has anyone installed an "In Lead We Trust" adjustable gas regulator?
Our 8" shop gun is ridiculous when running supers supressed.
Yes, obviously subs improve the situation a great deal, but the high bolt speeds still mean that a lot of noise comes back at me compared to a suppressed CZ scorpion or AR9.
It seems like the adjustable regulator would be an obvious solution, but since it requires opening the gas port up to the larger, hammer shattering first gen specification, I was hoping for some end user feed back.

FireMoth
02-26-2019, 04:11
So far as triggers, the Gen2 is less prone to hammer and disconnector breakage then the Gen1, due to a smaller gas port and lower bolt velocity. However, not all AR type triggers will survive. We have had great luck with the HyperFire 24c/3g, both because its a ridiculously fast trigger, and because the booster springs delay the bolt a little on opening, and ensure positive ignition.
BCM and Magpul AR grips seem to fit well, as do selectors from Radian and Battle Arms, and charging handles are available from Radian now.