16” MPX Carbine:

The idea of a full sized 9mm AR always intrigued me; the 9mm Tavor looked cool, too, but with the modularity of the MPX with all its barrels and rails and stocks, and the fact it’s a SIG sold me on it. I know the frustration behind the gen1, gen2, caliber exchange, magazine compatibility issues, but I was aware and kept out of it, for the most part, just observing. When I decided I wanted an MPX for sure, I was looking around for a Gen 2 MPX; this Carbine was the only gen2 I could find. The biggest plus, as mentioned here before when I asked, is that when I buy this one, I get the telescoping stock and don't have to find one of those. I ultimately plan on buying a 4" upper, and I'm sure that'll be hard enough to find without looking for a stock as well. I'll keep this stock and I may look for a folding one to add eventually as well.

I knew the new guns were out there, but none here in-stock and no one could order them. I was starting to look at ordering a gen2 pistol online, but then there’s the question if a gen 2 could have an aluminum rail system vs a gen 1 having a keymod rail. Either way – possible or not, I wanted one I could look at first. And the gun store Gunnies in Orem, UT had this one.

Oh, I know the question was asked, and I do see some light marks on the upper from the stock, but they rub off and definitely don’t show in photo. Close up of side:


I checked the Gen 2 stuff. The T shape on the side, the KM rail, the magazine, and wider chamber. I played around with it a bit at the store on a slow Tuesday morning with the employee behind the counter; we discussed some stuff, and I left to do a bit more research. Most online pictures of the MPX-C-9-KM-T show the 6.5” bbl with the 9.5” baffle flash hider thing on it, or a folding stock and a 16” bbl sticking out of the 8” handguard. In Sig’s brochure on SigEvolution.com, they don’t have a very good picture of the MPX-C, but it still shows an 8” or so handguard, longer barrel, and a very short-looking 3-prong flash hider. So, when I saw the longer 3-prong flash hider on this one at the store, I was intrigued by that as well, but definitely didn’t look too closely. Here’s what it looked like at the store from the side view with the full-length rail (which I also love):

3-prong flash-hider side with rail:

Once I got it home, however, I took the rail off – super easy to do – and immediately noticed that the extra-long flash hider isn’t there purely for hiding your flash… it’s pinned and welded.

Which can only mean one thing – it concludes that this “16 inch barrel” carbine, isn’t reallllly 16":

I went back online and looked at all the literature, forums, and discussion, but I don’t see where anyone says it’s a 14” bbl with a long flash hider. I must say, however, that I’ve never looked at a 14”-pinned 16” bbl rifle, so I’m not sure if there are many factory-made rifles with that or if people usually make them and have the barrel pinned and welded themselves.

Maybe I’ve mostly only ever read write-ups of those who’ve built a gun and they’ve chosen to go the 14” pinned route. This isn’t a huge letdown, since, as I said, I plan on getting a 4.5” upper when they come out – and I’ll use my suppressor on that, but I was interested in shooting this suppressed just to see, if nothing else, how much of the blowback rumors are true or false in either direction of overgassed or nothing at all.

Last little note:
Yes, the charging handle still slaps the receiver/upper. I knew about it, and don’t care enough to put random objects onto or into my gun to correct it. However, i figured someone might want pictures. this was their only one and it was on display, so It's probably been slingshot a couple of times, but I've seen non-display guns in online gun classified ads that look the same.


anyway - there she is. I can take other pictures if anyone wants one. Now to get to the range!

^^^ When I bought mine, I was told by a Sig rep that the barrel was 13.3" with a 2.7" flash hider.

quote:

Originally posted by immawake:
^^^ When I bought mine, I was told by a Sig rep that the barrel was 13.3" with a 2.7" flash hider.

That's about what I was thinking I was measuring. 13 and 3. but I don't know where the barrel starts in the upper and where it ends in the hider. thanks for the specification.

interestingly, but completely unimportant and irrelevant since I knew what I was buying... I just realized the tag on the box says it's a "fold," which I'd guess would mean a folding stock.

quote:

Originally posted by PorterN:
interestingly, but completely unimportant and irrelevant since I knew what I was buying... I just realized the tag on the box says it's a "fold," which I'd guess would mean a folding stock.

Can you post a photo of the carbine when you get the chance?

I've seen two configurations, one in which the bbl is slightly exposed (total length of the handguard looks ~12") and a second picture of the MPX carbine where the rail goes almost to the end of the bbl (~15").

Thanks!

quote:

Originally posted by LDD:



Can you post a photo of the carbine when you get the chance?

My write up is on the previous page with pics.

quote:

I've seen two configurations, one in which the bbl is slightly exposed (total length of the handguard looks ~12") and a second picture of the MPX carbine where the rail goes almost to the end of the bbl (~15").

Thanks!

The way the handguard and the extended flash hider are configured, id guess the actual rifled-portion of the bbl does end under the hand guard.

quote:

Originally posted by PorterN:

My write up is on the previous page with pics.

Thanks, missed that.

It appears that there have been some in-stream changes to the MPX carbine since the last time I saw it.

I was actually thinking about getting one of these instead of the pistol configuration, for SBRing since I liked the idea of a 12" handguard with a suppressor tucked inside (a la MP5SD). Chopping the bbl to 8" or less wouldn't have been an issue since the bbl should be rifled to at least 8".

The original carbine concept had an 16" bbl with the flash hider machined into the end of the bbl, and over-bored for ~8". This was done for two reasons. 1) The overbore on the barrel allowed SIG to use the same setting/balance on the carbine piston system as on the "pistol" MPX configurations (no tweaking necessary). 2) the flash hider on the end prevented someone from trying to add a suppressor on the end of the bbl since the bullet wouldn't have been stabilized as it traveled through the overbored part of the bbl.

It would be interesting to see if the barrel on your production model is still overbored.

I'm not completely taken by this new super-long handguard though.

As far as the marking of "Folding" I told SIG that the default configuration of the carbine should be the skeletonized folder and not the slider. This was back in 2014.

They decided to go with the slider for marketing/image reasons. I think anyone who uses both stocks will see the benefit of the folder over the slider.

quote:

They decided to go with the slider for marketing/image reasons. I think anyone who uses both stocks will see the benefit of the folder over the slider.

I'll definitely be keeping the slider, but i would love a 4" bbl with the folder for a super compact fungun

quote:

It would be interesting to see if the barrel on your production model is still overbored

Ill go check.

quote:

Originally posted by PorterN:
I did pick up the MPX Carbine today. MPX-C-9-KM-T. I took some pictures and will work on a write-up of just my first thoughts, and a couple of things I didn't expect with it. don't get me wrong, I am definitely happy with the purchase, though!

If you don't like the telescoping stock you can probably sell it for $800 on Gunbroker...then go buy the folding stock and a boatload of ammo!
:")

Tomorrow will be my 6 month anniversary having placed my order with Sig for the telescoping stock. It only took the ATF 5 months to deliver my Form 1 and Form 4. Sad to see that they are more organized then Sig.....

quote:

Originally posted by PorterN:
16” MPX Carbine:

Hot damn that thing is sexy!

I know what my next purchase is going to be.

The first image here shows the muzzle end - it's just dark in reference to the light I had on the bore - I don't have a borelight. It does have bore all the way to the muzzle.


I took off the handguard and put the camera right on the flash hider.


I will say one thing. When I took the handguard off this time, I happened to tap it against the 3-prong-flash-hider as I removed the guard. This muzzle device should now be referred to as a tuning fork, and nothing else. no other name will fit as well - no matter how well this thing hides flash. It won't do any other job better than tuning fork; this thing rings for days when tapped!!!

a 16" Carbine that isn't.

Ugh. Words used to mean something, Dimensions especially.

What is so damn hard about accuracy in such things?

Cool MPX, regardless.

Who knows when the short stuff will become available, so I sent my GEN1 to ZR Tactical Solutions. Now I have my 4.5in (K) sized variant.

ZRTS will...

Cut and thread the barrel 1/2x28
Standard A2 birdcage reamed to 9mm
Cut and Cerakote the handguard

$260 return shipping included. 3-day turnaround time.

https://www.zrtacticalsolutions.com

This message has been edited. Last edited by: armedjetflyer,

Link to ZTRS would be good to have

quote:

Originally posted by armedjetflyer:
I am tired of waiting for SIG. Who knows when the short stuff will become available, so I sent mine off to ZRTS. Now I have my 4.5in (K) sized variant.

That's pretty badass.
I will very likely end up doing the same thing.

quote:

Originally posted by HRK:
Link to ZTRS would be good to have

I just googled and it led me here:

https://www.zrtacticalsolutions.com/

edit: it's ZRTS - not ZTRS

[QUOTE]Originally posted by armedjetflyer:
I am tired of waiting for SIG. Who knows when the short stuff will become available, so I sent mine off to ZRTS. Now I have my 4.5in (K) sized variant.

Now waiting on the telescoping stock and the ATF.

Zach will...

Cut and thread the barrel 1/2x28
Standard A2 birdcage reamed to 9mm
Cut and Cerakote the handguard

$260 return shipping included. 3 day turnaround time.
--------------

Very nice! I guess I'm going to have to do the same except I think I'll leave the hand guard the stock length and fit the suppressor inside it.

quote:

Originally posted by Blackmoon1:

Very nice! I guess I'm going to have to do the same except I think I'll leave the hand guard the same length and fit the suppressor inside it.

^ this

quote:

Originally posted by creslin:

quote:

Originally posted by HRK:
Link to ZTRS would be good to have

I just googled and it led me here:

https://www.zrtacticalsolutions.com/

edit: it's ZRTS - not ZTRS

Lol I'm dyslexic