I have a question if anyone can help me with it. I know there have been issues with some aftermarket triggers functioning or fitting into the MPX lowers. I bought one that should work but my question is will the factory MPX trigger work in a regular AR Lower? I have another build going and that would save me some money on a lower parts kit

quote:

Originally posted by sleddog30:

quote:

Originally posted by JJexp:

quote:

Originally posted by gino d:
Is anybody else having trouble logging in to the ATFonline site to check their NFA status?
Once I put in my user ID and password, it just sits there and will not move to the next page

Your status won't change until the form is approved. You'll get an email notifying you that your form 1 has been approved when it finally happens. Until then, you're gonna be spinning your wheels logging on, and hoping to see a change.

Not quite true. My Form 1 for my MPX was Approved, but the pdf still showed pending. And I never received an email

As I got close to my 120 days, I started logging in every business day to check the status. On June 14 when I logged in to check the form was now under "APPROVED". But the pdf still showed pending. It was approved, on the 14th but the pdf generation system messed up. It took 10 days of using the "ask the Expert" system and emailing to get it changed. I had to wait for the examiner to generate it again.

So as your 120 days starts getting close, log in and check. And if the pdf system messes up, keep contacting them until you get the approved form.

You say to keep contacting them. At what e-mail address should I be using to contact them? Thanks,

New here, been trolling since the creation of this post. Decieded to finally join and submit my 2 cents on the MPX. I currently have a gen 2 pistol with psb. And had a gen 2 carbine with 3 prong flash hiders (avoid that one if you can get the updated flash hider carbine) Three prongs are noisy/ ring.

Love both these guns figured Id post to save some people a headache. As I thought originally to cut down the carbine to a sbr, I would advise you its now cheaper to just get a pistol and add whatever you to it like a tele stock, or longer hand guard. With that being said heres the current prices of what Sig has told me on the phone: Barrels any length $600, complete uppers $1000. Hand guards 4,8,15"= $129, $149, $159. Originally a $75 barrel chop seemed the way to go, but have heard the taper of the barrel on the carbine requires additional work, also the gas system on the carbine is different and from reading elsewhere and talking to sig, was advised not to cut below 8" (gamble either way imo with the $600 barrel price)


Im also impressed no ones talking about the new telescopic arm brace from sb tatical, its on their main page, but not for sale yet, looks just like the tele stock. (any input?)

Note on the tele stock, original mpx-k and carbines came with a model specific tele stock, it is longer! And sig is too cheap to keep making it, so they made a mcx/mpx tele stock that is the only one offered now. Its shorter to clear the brass deflector on the mcx. I wish they made a version for each as the telestock on the carbine "feels" short.


My only question: Does anyone know where to get the keymod pistol grips with the little tang on the end/ hand stop???

quote:

Originally posted by louie:

Note on the tele stock, original mpx-k and carbines came with a model specific tele stock, it is longer! And sig is too cheap to keep making it, so they made a mcx/mpx tele stock that is the only one offered now. Its shorter to clear the brass deflector on the mcx. I wish they made a version for each as the telestock on the carbine "feels" short.

You are incorrect on this statement. The length of pull for both telescoping stocks is exactly the same. I had both, I measured them. The only difference is on the original, the ends of the rods stuck out further when opened and on the new MCX compatible tele stock they are recessed in to the mount to clear their ejection port as mentioned.

Is anybody making an aftermarket charging handle yet?

I have a Gen 2 with the Ambi handle and I noticed that when you pull on the left tab it doesn't unlatch the right side hook, making it very difficult to charge and causing the receiver area to wear away at the hook interface. If you pull on the right side tab then the hooks on both sides unlatch properly.

Are the different sized handguards available yet? $600 per barrel assembly, ouch! Mine is chopped to 4.5" now but started as a 8/9" setup. For $600 could I make it a carbine and have no functional issues? Just a thought and not a priority, but it's good to know this could be done...

Gen 2 MPX here, Gen 1 and 2 mags have worked fine, no issues to date suppressed or otherwise. Today I'm at 120 days for my NFA SBR paperwork, come on already!! ;-)

Thanks!

quote:

Originally posted by Drew816:
Are the different sized handguards available yet? $600 per barrel assembly, ouch! Mine is chopped to 4.5" now but started as a 8/9" setup. For $600 could I make it a carbine and have no functional issues? Just a thought and not a priority, but it's good to know this could be done...

Gen 2 MPX here, Gen 1 and 2 mags have worked fine, no issues to date suppressed or otherwise. Today I'm at 120 days for my NFA SBR paperwork, come on already!! ;-)

Thanks!

$600 for a barrel is ludicrous. I'd pay $600-800 for a complete barreled upper but not for just the barrel alone. That's half the cost of a Sig Legion 226 right there...

quote:

Originally posted by Brett B:
Is anybody making an aftermarket charging handle yet?

I have a Gen 2 with the Ambi handle and I noticed that when you pull on the left tab it doesn't unlatch the right side hook, making it very difficult to charge and causing the receiver area to wear away at the hook interface. If you pull on the right side tab then the hooks on both sides unlatch properly.

Don't know if aftermarket handles are out yet, but for those with ambi handles, check the roll pins on the top side. I noticed that one of them was sticking out a ways, that when the handle was released, it was scraping the underside of the upper receiver's charging handle tunnel - just the bit that sticks out a little. I tapped the roll pin back so it was flush with the rest of the body.

quote:

Originally posted by Drew816:
Are the different sized handguards available yet? $600 per barrel assembly, ouch! Mine is chopped to 4.5" now but started as a 8/9" setup. For $600 could I make it a carbine and have no functional issues? Just a thought and not a priority, but it's good to know this could be done...



Gen 2 MPX here, Gen 1 and 2 mags have worked fine, no issues to date suppressed or otherwise. Today I'm at 120 days for my NFA SBR paperwork, come on already!! ;-)

Thanks!

Spoke with sig last week and they said "some barrels are available". $600 each reguardless of size.

Gun broker has the uppers in 8" config for $1000

And the handguards are available and start at $129 for the 4"

So hypothetically speaking, you have to spend $729 for a 4" barrel and handguard. Or more for the 16" and that hand guard.

Having bought both the carbine($1599) and pistol now ($1399). I would just wait for more things to become available or cheaper. Or better yet buy a entire other mpx.

If they ever make the conversion kits for .40 and .357 Im sure some barrels will come up second party for grabs.

Faust245, good to know on the telestocks! I have seen one and it looked different than my carbine but couldnt figure out what it was! Now on my call with sig they told me it was a half inch shorted and not noticable....

Sig's claiming that the LEO price for the MPX 8" pistol is $1468. Aren't they retailing for less than that??

quote:

Originally posted by louie:

Spoke with sig last week and they said "some barrels are available". $600 each reguardless of size.

Gun broker has the uppers in 8" config for $1000

And the handguards are available and start at $129 for the 4"

Right now, those items are available for backorder only. Three weeks ago when I placed my order I was told that they're anticipating shipping by end of August, but they're still waiting until they're able to fulfill orders for the K model.

quote:

Originally posted by Brett B:
Is anybody making an aftermarket charging handle yet?

I have a Gen 2 with the Ambi handle and I noticed that when you pull on the left tab it doesn't unlatch the right side hook, making it very difficult to charge and causing the receiver area to wear away at the hook interface. If you pull on the right side tab then the hooks on both sides unlatch properly.

Same issue here. Left side doesn't work. It's an Ambi handle in name only.

Looks like they are shipping MPXs with carbon fiber hand guards now?
http://www.gunbroker.com/item/569863749

quote:

Originally posted by Bigcat100:

quote:

Originally posted by Brett B:
Is anybody making an aftermarket charging handle yet?

I have a Gen 2 with the Ambi handle and I noticed that when you pull on the left tab it doesn't unlatch the right side hook, making it very difficult to charge and causing the receiver area to wear away at the hook interface. If you pull on the right side tab then the hooks on both sides unlatch properly.

Same issue here. Left side doesn't work. It's an Ambi handle in name only.

All is good on mine. No matter which side I pull they both unlatch. Came on Gen 1 which is unusual. Manufactured Sept. 2015

Update on the new pistol. I sighted it in the other day and had to lower the front post alot. It's on target now. So backed up to 25 yards... And hitting way left. Moved the rear peep left a good bit, but still needs alot more. Things gunna have more canted sights than a bad ak47. Anyone move their irons that much?

Hello all, I have a chance to buy a MPX Gen 1 8" locally that is NIB at a really good price.

My question....is there a reason I'd be better off with the newer Gen 2? I don't care anything about caliber exchanges and will only want to fire 9mm out of it.

Was there design and/or performance improvements in the Gen 2, or was the change solely to introduce the caliber exchange option? The SIG video on Youtube says not to use Gen 2 9mm mags in the Gen 1 but I'm guessing they work just fine anyway?

The one I'm looking at comes with a quad rail hand guard (and no stock) and the Gen 2 comes with a keymod guard. Not sure why Gen 1 has a quad rail on such a short barreled gun but....there it is.

Anyway, would appreciate your thoughts. Is there a reason not to buy the Gen 1? Thanks.

I have a gen 2 mpx that is almost brand new and I am experiencing a problem with the bolt not locking to the rear on an empty magazine. So here is what I have tried so far.... 3 types of ammo, two different magazines (20&30rd) and the same problem persists. The strange thing is that when manually pulled back the bolt will atay to the rear on an empty mag, but when shooting the bolt does not lock to the rear. Has anyone experienced this problem before? Does anyone have any places to check before I give sig a call and try to send it for a checkup.
Thanks in advance.

I received my 3 pack of gen 1 mags the other day and finally had an opportunity to test all 3 in my gen 2 MPX. I'm happy to report that all 3 gen 1 mags functioned flawlessly.

quote:

Originally posted by louie:
Update on the new pistol. I sighted it in the other day and had to lower the front post alot. It's on target now. So backed up to 25 yards... And hitting way left. Moved the rear peep left a good bit, but still needs alot more. Things gunna have more canted sights than a bad ak47. Anyone move their irons that much?

range report, tried differnt ammo, and got her sighted in from a bench at 25 yards. also the gun fell out of a book bag, maybe this corrected my canted sights lol! Im probably 400 rds in now, no fails to feed or fire. Very fun with a few 6" steel plates at 20 yards. Also recieved a key mod pistol grip hand stop, the screws that come with it are counter sunk style, dont know why, nothings countersunk on the handle. Essentials kit 3 mag pounch came in also.... I need more ammo!

quote:

Originally posted by dwd1985:

quote:

Originally posted by nreno88:
I have a gen 2 mpx that is almost brand new and I am experiencing a problem with the bolt not locking to the rear on an empty magazine. So here is what I have tried so far.... 3 types of ammo, two different magazines (20&30rd) and the same problem persists. The strange thing is that when manually pulled back the bolt will atay to the rear on an empty mag, but when shooting the bolt does not lock to the rear. Has anyone experienced this problem before? Does anyone have any places to check before I give sig a call and try to send it for a checkup.
Thanks in advance.

The piston spring is still stiff and being broken in. Lock the charging handle to the rear and let it sit a day or two. Then try again.

Thanks, I'll give that a try!