quote:

Originally posted by MajorLonghorn:
I'd heat the nuts with a soldering iron to soften the Loctite before unscrewing, just to be safe.

Thanks for the tip. I've got a pretty strong heat gun which I think will work for the job.

Looking at the pictures online though, it surprises me that Sig would put those captive nuts in an area that isn't very well supported as evidenced by the slot right above them.

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

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.

Does anyone know if you can remove the ambi safety and make it a left side only? I got to get my hands on an MPX but didn't like that the safety hit my trigger finger when turned to fire.

quote:

Originally posted by Phantom229:
Does anyone know if you can remove the ambi safety and make it a left side only? I got to get my hands on an MPX but didn't like that the safety hit my trigger finger when turned to fire.

It's held in by detent just like a normal AR safety is. In fact, you can replace it with a left-hand only AR selector if you wish (or BAD-ASS, etc).

IIRC part of it does potrude from the side of the receiver even with the lever taken off. It won't look super-sleek.

Why not just swap sides with the levers?

quote:

Originally posted by LDD:

quote:

Originally posted by Phantom229:
Does anyone know if you can remove the ambi safety and make it a left side only? I got to get my hands on an MPX but didn't like that the safety hit my trigger finger when turned to fire.

It's held in by detent just like a normal AR safety is. In fact, you can replace it with a left-hand only AR selector if you wish (or BAD-ASS, etc).

IIRC part of it does potrude from the side of the receiver even with the lever taken off. It won't look super-sleek.

Why not just swap sides with the levers?

Ok good to know. If I swapped sides, then it'd become more of a problem.

My MPX gen 2 arrived on Monday. Picked it up from the FFL today and was able to get to the range and function test / sight-in a few hours ago.

Initial thoughts? Wow. This thing is great. At 25 yards (outdoor range, nothing shorter than that), the MPX shot quite low. Had to lower the front sight several revolutions, and gave windage about 5-6 clicks to the right to get POA=POI. After that, zeroed a cheap TRS-25 RDS I had laying around. Once that was done, I was getting 1.2-1.5" groups freehand using 115gr CCI/Speer brass cased ball ammo.

Recoil impulse was also very nice and smooth under rapid fire.

All in all, I'm very impressed and happy with my purchase. For some reason, I've always had bad luck buying guns over the internet, and usually have to send back to the manufacturer for one reason or another (my last Sig - a Scorpion 1911 was no exception), but this one ran like a top. All I did was lubricate before loading my first mag and enjoyed 200 trouble free rounds.

Now my only concern is removing the barrel. I've read of a few - perhaps only 1 or 2 folks - having problems removing the two barrel bolts due to excessive locktite thus fracking up the receiver when the bolt spins in place. I plan on removing the barrel shortly to have it chopped. I'll use a heatgun first and maybe some 90+% denatured alcohol to soften the loctite before I do it. Apart from that, any suggestions on how to prevent the captive nuts from spinning and damaging the receiver?

BTW, as I'm planning to SBR this pistol, I've been thinking about reusing the original pistol brace/folding mechanism. How is the "buffer tube" attached to the mechanism? I was able to remove the brace from the tube earlier and noticed the tube has a place for a wrench to attach at the end. I'm assuming the tube is just screwed into the end and torqued down? Is there any loctite there?

If you've removed this tube before, how did you secure the folding mechanism to ensure enough torque gets transferred to remove the tube?

quote:

Originally posted by amstel78:
If you've removed this tube before, how did you secure the folding mechanism to ensure enough torque gets transferred to remove the tube?

No loctite, just make sure you use a good (not worn) torx wrench. I left the folding knuckle attached to the gun, and unscrewed it while holding the MPX.

quote:

Originally posted by LDD:

quote:

Originally posted by amstel78:
If you've removed this tube before, how did you secure the folding mechanism to ensure enough torque gets transferred to remove the tube?

No loctite, just make sure you use a good (not worn) torx wrench. I left the folding knuckle attached to the gun, and unscrewed it while holding the MPX.

You're referring to the torx screw that's underneath the folding mechanism? At the opposite end of the actual tube under the brace, there's a place to attach a box/crescent wrench.

Was curious if anyone knew the specs of the 8" barrels? Are they CHF? I don't believe chrome lined - perhaps melonited inside? What type of steel used?

Couldn't find any barrel specs online.

One thing I should note with my sample is that there's a tiny gap between the upper and lower receivers. You can see daylight between the two. As a result even with the spring plunger tensioner in the lower, there's a slight wobble between receivers.

It's probably a non-issue for most as it is for me, and can likely be attributed to tolerance stacking, but felt I should mention it. My gun was made on 2 May, 2016.

Anyone else see similar with their gen 2 guns?

What's the latest on the K version? Tomorrow will be July 1.

When I called a couple weeks ago I think the Sig rep told me the K is in production and should be available. That being the case he said the 4.5" handguards shouldn't be too far behind

The MPX K is showing up on websites but I haven't found one in stock. Do a google search for this model MPX-4B-9-KM-SBR

Prior post was for the 8" SBR, try this one for the 4.5" SBR

MPX-K-9-T-KM-SBR

quote:

Originally posted by amstel78:
One thing I should note with my sample is that there's a tiny gap between the upper and lower receivers. You can see daylight between the two. As a result even with the spring plunger tensioner in the lower, there's a slight wobble between receivers.

It's probably a non-issue for most as it is for me, and can likely be attributed to tolerance stacking, but felt I should mention it. My gun was made on 2 May, 2016.

Anyone else see similar with their gen 2 guns?

I have the same gap on my Gen 1 Pistol and Gen 2 Carbine and both make a small clacking noise due to the movement. The only noise that I wanted to hear was a boom from the muzzle end so I purchased some AR-15 Pivot Pin shims from triggershims.com. I used a 2-sided adhesive film so that the shims would not fall out every time I removed the upper, and both guns are now tight and quiet! The gap is still there just like every other MPX but the movement is gone!! Excellent product!!!

quote:

Originally posted by ivy6t5:
I have the same gap on my Gen 1 Pistol and Gen 2 Carbine and both make a small clacking noise due to the movement. The only noise that I wanted to hear was a boom from the muzzle end so I purchased some AR-15 Pivot Pin shims from triggershims.com. I used a 2-sided adhesive film so that the shims would not fall out every time I removed the upper, and both guns are now tight and quiet! The gap is still there just like every other MPX but the movement is gone!! Excellent product!!!

Thanks for confirming. The gap seems like either a design element (unintended?), or just due to stacking.

Anyway, my gun runs perfectly. The gap is cosmetic and doesn't bother me. The wobble doesn't affect accuracy either. As long as the weapon fires when the trigger is pulled and I can hit what I'm targeting, then I'm OK with it.

The M4 I was issued years ago was in terrible condition cosmetically and rattled like a copperhead. Still worked fine!

Now if only my gen 1 mags would show up...

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.

Same thing happened to me but I sent them a message and they fixed it within a day.