I've been toying with the idea of class 3ing a 9mm sbr of some type.

What are you guys opinions of the quality, functionality, and durability of the Sig MPX in 9mm SBR?

Also how well do these feed hollow points?

Thanks!

I purchased a MPX pistol over four months ago and have never fired it yet. I'm waiting for the tax stamp to get approved and will put a folding stock on it once it arrives. I feel that without going the SBR route it's a totally useless firearm.

I dislike the pistol braces with a passion, especially since the BATFE changed their position and now ban the shouldering of them. I've always been a fan of SIG firearms since owning a Browning BDA .45 back in the mid-1980's. They make excellent firearms and that's one of the reasons I went that route.

The other reason I went with SIG is I didn't want to spend up for a HK-94 or one of the clones. I spent just over $1200.00 for the SIG MPX pistol, $200 for the tax stamp application and under $200 for a folding stock. Magazines were expensive, but not more so than HK magazines.

To me I'm getting a modern locking bolt 9mm built by a reputable company that will stand behind it's product. Only time will tell how well it holds up. SIG introduced this firearms with the hope of competing against the H&K MP5 series of sub guns, I expect it to do well.

I have a pistol that I registered as an SBR.  I really like it.  Has been 100% reliable.

I SBRed one of mine.  100% reliable, suppressed and unsupressed.  I've never fired a single ball round out of it.  It has exclusively fired 124 grain Federal Hydrashok with zero issues of any type.

This is my favorite fun gun.  And even my family members who are FUDD gun champions love this thing too.  I had one person look at it when I brought it out, snarl, and ask why I have that.  I handed it to him and a full mag.  It's SBR'd with a Trijicon MRO on it (can is in jail).  By the time he was done with the mag he was smiling and handed it back saying how fun it was.  I told him "THAT" is why I have it.

If you are familiar with the AR platform, you can pick it up and use it immediately.  No acclimation required.  And because it's a full locking bolt short stroke piston design, you get way less blowback suppressed than roller lock SMG's.  And because it's 9mm...it costs pennies to shoot.  But because it's not .22lr you can actually use it for home defense if you wanted (or maybe horseback hog hunting ).  I'm really a big fan of the MPX, I just wish Sig would get their heads out of their asses.

mpx and larue trigger is awesome.  just been using fmj

Ah yes, forgot to mention I have a Larue MBT in mine as well...with a B.A.D. safety and Larue A-PEG too

Just added a 4.5" integrated 3lug barrel to it today as well!!  Now for the ATF to get off their ass and give me my can(s) !!

I really like mine as an SBR.  It is controllable and the manual of arms is nearly the same as an AR so it is easy to get used to.  I shoot mine suppressed 95% of the time and have not notices the blow back issues some others have experienced.  all in all it is a great gun for me and I am looking forward to running it in PCC.  Additionally, with mags being on special more and more often it is a lot easier to pick up extras.

love mine... had the barrel chopped to 4.5 inches and run a can undernieth the handguards... I look at it as the next evolution of the MP5SD... I only run 147 grain lawman out of it... super quiet and my new favorite SBR

I have an MP5 clone SBR as well... it has more panache, but isn't as capable as the MPX in its suppressed config

What do you feel makes the MPX more capable?

My Gen1 MPX SBR is hands down my most fun rifle I've every owned or shot.  It gives everyone giggles who shoots it. :)

I have approximately 8k rounds of all bullet weights, suppressed and un-suppressed, through it without a single malfunction.  With that being said, I was lucky enough to purchase a Gen1 which is according to the internet commandos more reliable than a Gen2.  I have no experience with the Gen 2's but if you do some searching there is quite a lot of bitching about their reliability.  

My suggestion is to get a Gen1 pistol/sbr and shoot the hell out of it :). Good luck OP!

Pic for reference :)

I've had mine for a little over a year and it's been flawless. I have a Romeo 4, factory collapsible stock, and FA BFSIII trigger. I have only used 115 FMJ ammo so far. I have a Octane 9HD with a three lug waiting for me when I return to Ohio. Fun gun.

compared to the mp5 I have... the mpx with the short 4.5 inch barrel and suppressor under the handguard makes it much shorter than the mp5 with a suppressor on the end. Trigger is better on the mpx. Controls are better on the mpx. ergos in general are better on the mpx. ease of optics mounting, BUIS, light mounting , etc...

just a better evolution of the subgun

the mp5 isn't going anywhere... and id like to get a zenith to sbr and make an mp5k clone... just fyi

Possibly the best sub gun ever built.

Do you by any chance have pics? Would love to see the 4.5" w/ suppressor setup...

I have questioned for years, why no one has ever done this.

Excuse the quality of the iPhone pics... the MPX has a 4.5 inch barrel with trilug to accept the griffin can (so I can swap between the MP5 and MPX)

Posted pictures with my special weapons mp5 clone and .300 blackout 8.5 inch Noveske with and without suppressors...

as you can see, the MPX is a very small package with the suppressor and the ease of mounting an optic, light, and IR laser (if you wanted to use it for night time shooting) makes it a no brainer in terms of having a very versatile pistol caliber carbine SBR... with 147 grain subs, is very quiet, I believe more so than my .300 BLK shooting 220 grainers.

As far as accuracy goes, the MP5 and MPX are both about 3-4 inch guns at 50 meters using 147 grain lawman tmj and 147 grain freedom munitions reloads... they group better with 147 grain HST, about 2 inches or so which is great

of course, they are CQB guns I guess... so they shoot for what they do best

all in all, I LOVE my mp5 but if I had to keep one, well, the MPX gets the vote... but I still want an MP5SD...

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Sig MPX 4.5" w/ Rugged Obsidian

I know this is the SBR forum but I would like to know if I buy the MPX pistol and later on want to convert it to Full auto after I pay my tax stamp! Can the MPX be converted pretty easily and cheaply? Or is it better to buy a factory full auto already done?

I'm gonna guess if you're asking, you do not have an 07 manufacturer SOT and therefore cannot create any NFA machine guns so, no you can't make it full auto.