Looking for user experience & feedback on the Sig MPX 9mm. I have an option on a 8” barreled 9mm variant. What are the differences between Gen 1’s vs Gen 2’s ( I suspect its caliber exchange )if available? How much is too much to pay for one? Thank You good folks? Keep safe wherever you are..

I like the MPX. Mine is a Gen 1. The magazines differ between Gen 1 and Gen 2, and Sig utterly failed on their promise to deliver caliber exchange for Gen 1.

I like the MPX. Mine has an 8" barrel, folding stock, aftermarket trigger, and presently a sig red dot sight on it, and a light.

I don't know what's too much to pay, but new I see them in the 1,500 range, down to 1,200.

I'd like to pick up a 16" MPX for pistol caliber carbine shooting at steel matches, for fun. Perhaps if a good deal comes along.

I've a few of them. carbine and pistol. Caliber exchange ended up being a pipe dream. Mine are 2. Been absolutely flawless in terms of operation. many thousands of rounds. Originally the pistol was 4.5" but I easily swapped it to 8" as I need a little room for my hands on these. Used the carbine for steel matches for awhile and its been fine, though at this point I've been using a pistol with brace as its way better. Went to the Geissle trigger recently and its an improvement, but I haven't sorted the recoil spring issue yet. My big complaint would be mag prices compared to the alternatives like the ar9 with glock mags or the CZ with $20 factory mags.

I've got the Gen 2 8" pistol with collapsible brace. Primary Arms red dot on top. It's the most fun gun I have to shoot. Everyone that shoots it gets a huge grin on their face! I've used Gen 1 & Gen 2 mags with no issues. It's ate everything I've thrown at it.

I got mine a few years ago before prices went up. I think I paid around $1,100 + $200 for the brace.

I have a gen2 pistol with folding brace. I think it was $1200 new? I've had it for awhile, I can't remember who I had cut down the 8" barrel to 4.5".

No issues with gen1 or gen2 magazines.

Mine is a Gen-2 8” pistol that I SBR’d. Many thousands of rounds through it, a majority of them suppressed now, and it’s always been flawless. It’s one of the most fun guns that I own. I’m still running an original Geissele SSA (that I installed long before it was recommended not to) and it’s still chugging along just fine.

When suppressed and shooting PRVI 158 grain subsonic it’s quieter than any of my buddies 300BO rifles w/subsonic ammo. The mags are more expensive but I’ve never had the feed lips crack on one, an issue which the cheaper Scorpion mags are known for.

I shot it side by side with my buddies new HK SP5 several weeks ago and the MPX recoil impulse was smoother/more controllable. The SP5 was very cool and retro, and is of course the standard by which all sub-guns are judged, but otherwise I preferred the MPX in about every way for ergonomics and shootability. Currently running the folding stock as I like the longer LOP compared with the telescoping stock.

My MPX is my favorite weapon to shoot. I love the size of the weapon and accuracy. I have some Gen 1 and Gen 2 mags and both work fine in my gun. The only thing I don't like about the MPX is the safety lever on the right side.

My buddy bought the CZ carbine and we sometimes go to the range together. I like the Sig over the CZ myself.



My Spikes AR9 is also fun, but the Sigs action is much smoother.

I had a CZ Scorpion and traded it towards my Gen 2 MPX. The MPX is much better in my opinion. Soft shooting, reliable, familiar manual of arms. If you can stomach the price I highly recommend it.

I appreciate the quick response & intelligent feedback. The insight is invaluable. Thank you

I've shot a full auto MPX. I didn't find it markedly better than my SBR Scorpion sans the giggle switch. For the price, I'd buy a CZ and SBR it. Not to mention that mags are cheaper and I trust CZ to still be supporting the Scorpion when SIG has moved on to the next new thing.

Had a Gen 1 and sold it. Between the charging handle sagging and peening the upper combined with Sig's lack of follow through on the caliber changes I was over it. Prices seem to have gone up and there's still no ability to change calibers.

Here is my 8" gen 2 carbine cut down and sbr'd next to 5" PTR 9kt sbr'd



Now with cans:


So now for the feedback.

I prefer the 8 Inch. I can really let them humm downrange with an 8" gun. The MP5 and the MPX in its previous 16" are too small and too big respectively. Find an 8" or buy an ILWT 8" barrel and SBR the gun.

I Originally cut down my 16 tuning fork to 8" and put a trilug adapter on it. I liked it enough I sprung for the ILWT gasblock and barrel with trilug. I picked up the carbon fiber rail cover here on sig forum. I have not messed with the trigger. It is a fine stock trigger. I don't need to drop it down to 3lbs for the plinking I do with it.

I ran 1500ish,maybe 2k if memory serves before the firing pin broke. Sig sent me a new bolt carrier set up. It has 5k through it since. It did not like geco 115 grain ammo at all. Though when I chrono'd it, i had speeds of 1100 to 700 fps out of the geco. So I have chalked that up to the ammo. I have 4 or 5 30 round MKII mags, and 15 10 round mk 1 mags converted to 23/24 round mags that I load to 2. They all work well.

Things I would change other than 8" sbr. Charging handle, rail cover, make sure it can do a tri lug mount.

Things I would not change Collapseable stock (side folders are bulky).

Just added a new ambi charging handle and lifter block, as well as an AR telescoping stock to my 8" SBR. I used the SIG factory folding knuckle.

I really like my MPX SBR (started life as a pistol). Super soft shooting and stupidly accurate, especially with my 124gr JHP handloads. I've got a Romeo on mine. I've had the thing for maybe 4 years (5?) and have never had a single failure of any sort. Flawless rifle with both Gen 1 and Gen 2 mags. SIG closed out the Gen 1 mags in a 3 pack a long time ago and I snagged them at an actually fair price.

I originally had the factory collapsible stock on there that I won in a karma, but I thought I'd see if I prefer an AR folder.

My only complaint at all is the factory trigger is shit. Can't bring myself to replace it with a silly expensive Geissele or Timney, especially since I can't go to the range until Coronageddon is over.

Eventually I'll get a suppressor for it, but it's great as is now.