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SIG SAUER MPX (Update: Exclusive Non-NFA version P7)

This topic can be found at:
https://sigforum.com/eve/forums/a/tpc/f/630601935/m/4610068653

March 18, 2016, 08:05 PM
tbuck
SIG SAUER MPX (Update: Exclusive Non-NFA version P7)
Ok I think I'm done until my GEN2 K handguard shows up. It's ordered along with the grip.



March 18, 2016, 09:25 PM
Dano36
Can I ask where you purchased the CF pieces for the rails?
March 18, 2016, 09:39 PM
tbuck
There centurion arms cmr rail covers. I got mine at operational parts. I think they were the last set. Comes with 3 panels. I used the screws that came with my sig rails. Cut one rail down to fit behind the hand stop.
March 18, 2016, 10:22 PM
creslin
quote:
Originally posted by scubacuba:

VERY INTERESTING! Cutting the barrel on the 8" model to 4.5" and configuring it as you've described above (with a somewhat covered suppressor) is something I had not considered. I have a Ti-Rant I'd love to put on it and I think it would look very nice like that!


That's what I have planned for mine as well. I have an omega 9k in jail - once it's approved (or simply getting close to approved) I'll be shipping the gun off to get that barrel chopped down and threaded. Can't wait!





This is where my signature goes.
March 19, 2016, 07:58 AM
g8rbreath
MPX Gen 1 4.5" barrel cut and 8" rail
3 lug under the rail to Tirant 45S
Not greatest photos will post more later
[IMG:left] [/IMG]

[IMG:left] [/IMG]
March 19, 2016, 05:47 PM
Drew816
quote:
Originally posted by ivy6t5:
Here is a 39-cent solution to the cold/hard cheek weld on the KM stock. I purchased a 1-foot length of 3/8" I.D. x 1/2" O.D. Clear Tubing from the plumbing department at Home Depot for 39 cents. I cut off a 5-1/2" length and slit it on one side down the length of the tube and placed it on the top rail of the KM stock. Much better feel - softer and warmer!



Great idea. No doubt SIG will make a version of this and market it for $39, SIG Logo and all. And many would probably buy it too! ;-)


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March 19, 2016, 05:49 PM
Drew816
quote:
Originally posted by tbuck:
Ok I think I'm done until my GEN2 K handguard shows up. It's ordered along with the grip.



SNIP!


That weapon looks fantastic! With the KM stock and 4.5 " barrel w/ flash hider, what's your total length? Just curious what you ended up with for your SBR paperwork which I'll be doing shortly here myself...

Thanks!


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March 22, 2016, 10:37 AM
obiefox
My factory Gen 1 K SBR came in last week. The form4 will be filed this week.


March 22, 2016, 10:58 AM
AggiePhil
Here are a couple videos of me and a buddy shooting two different MPXs last weekend. One was a cut down full-auto K, the other was semi-auto 8". Both are suppressed. I was AMAZED at how controllable this gun is. Gotta get me a Keymod K now.

https://youtu.be/S09snpHOIf4

https://youtu.be/3a_ALlA6uhU
March 22, 2016, 12:52 PM
Drew816
Ok, I want to cut down my barrel to the right length so that it's flush with the 4.5" K hand guard, not including a flash hider. I'll generally have a thread protector on the barrel, and pull it off and install my suppressor when shooting.

SO what length do I have to have my barrel cut down too in order to have it be approximately flush with the end of the K hand guard?

From the pictures I've seen, it appears a 4.5 barrel is in fact inside the hand guard, and it extends out only because of the flash hider.

So do I need to go 4.75", 5" or?

Thanks!


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March 22, 2016, 12:56 PM
Drew816
quote:
Originally posted by AggiePhil:
Here are a couple videos of me and a buddy shooting two different MPXs last weekend. One was a cut down full-auto K, the other was semi-auto 8". Both are suppressed. I was AMAZED at how controllable this gun is. Gotta get me a Keymod K now.

https://youtu.be/S09snpHOIf4

https://youtu.be/3a_ALlA6uhU


Cool stuff, thanks for sharing!


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March 22, 2016, 01:03 PM
Cntrl23
Received the keymod MPX foregrip/hand stop today, ordered at the end of January. Seems very nice, now to wait for the 4.5" hand guard!


March 28, 2016, 07:12 AM
mpxgeek
quote:
Originally posted by SuperPollito:
quote:
Originally posted by dwd1985:
quote:
Originally posted by SuperPollito:
FYI (and this may depend on examiner) but my Form 1 was rejected because I listed the item as Sig MPX-P rather than Sig MPX.


Yup, I had the same thing happen. Re-submit with just "MPX", then call your examiner with your old and new case numbers. They will expedite the
process, and it should only take an extra 4 or 5 days.


That's what I ended up doing as well. Only took 3 hours or so but we got it worked out. After redoing the paperwork, I believe the MPX-P was an option in their dropdown menu, i.e., not something I personally put in. But at any rate, all is well and my lovely telescoping stock can now be mounted.


I put MPX-PSB and I received my stamp on Thursday with no issues....guess I got a lenient examiner!
March 28, 2016, 10:34 AM
ctsheepdog
Help me choose a RDS mount.

Based on some luck, I am getting an Aimpoint T2 at an incredible discount. What I need to do now is decide how to mount that on my soon-to-be-ordered MPX.

What mount should I use if I think this sight will stay on the MPX making QR helpful but not necessary?

I "think" I would like to pull off absolute co-witness with the stock MPX sights, if possible. But I am willing to be dissuaded if the height requirements for absolute co-witness leads to cheekweld/head position sighting challenges.

I have not decided on a stock once the SBR stamp is available. Leaning more toward telescoping/collapsing rather than swinging (KM).

I can get the Aimpoint LRP at the same discount as the sight.

I REALLY like the look for forward cant of the Fortis mount that Steve has used.

I have looked at the Scalarworks LDM as well.

And then there are the Larue options, but those are all QR, but come in a variety of heights.

Or I can go cheap with the RDSM-4H (ACW) to start.

Any advice appreciated.

ETA: Does anyone have a current ETA for the MPX-K local shops?
March 28, 2016, 12:11 PM
LDD
quote:
Originally posted by ctsheepdog:
I "think" I would like to pull off absolute co-witness with the stock MPX sights, if possible. But I am willing to be dissuaded if the height requirements for absolute co-witness leads to cheekweld/head position sighting challenges.


The factory sights on the MPX are shorter than standard same-plane AR-15-height sights. A sight base that is normally "Absolute" may actually result in a "lower 1/3" when used with the factory MPX sights.
March 28, 2016, 01:06 PM
ctsheepdog
Thanks guys.

dwd, are you talking about this mount or just the spacer (adapter) shown above the micro mount?

https://danieldefense.com/moun...lute-co-witness.html


March 28, 2016, 01:51 PM
ctsheepdog
quote:
Originally posted by dwd1985:

Just the spacer itself. I ordered the lower 1/3rd mount, which is an absolute mount with a spacer you can add on to raise it to lower 1/3rd. I used the absolute mount on one H1, and then used the spacer with a factory mount on the H1 I mounted on the MPX.
So Aimpoint factory mount AND the DD spacer on the MPX? And you got absolute with both combinations?
March 28, 2016, 03:15 PM
ctsheepdog
For a reformed engineer, I can be a dump sh1t at times. Frown

Thanks.

Anyone else with thoughts on T2 mounts in MPX?
March 28, 2016, 08:56 PM
Blackmoon1
quote:
Originally posted by ctsheepdog:
For a reformed engineer, I can be a dump sh1t at times. Frown

Thanks.

Anyone else with thoughts on T2 mounts in MPX?


I would recommend the Trijicon MRO. I have them on all my SBR's and AK-74. It's the best RDS I've ever had and I like better then the Aimpoint. Whichever one you get I would also recommend a QD mount. I use the American Defense.
March 30, 2016, 10:37 AM
QuietMPX
Hey all, I just wanted to introduce myself and thank you guys for the info in this thread. It's has been a great resource in figuring out what to buy and how to do my build. I ordered a MPX-P that should arrive at my FFL today. My plans are to SBR it with the telescoping stock (though I wish Sig hadn't switched to the shorter rails, I'll take what I can get.) I've got a Rugged Suppressors Octane 45 that's on it's way to the retailer and I chose that can based on what I read in this thread. I plan to e-file the forms under my trust so that, hopefully, everything will be granted, or at least submitted, prior to 41p going into effect.

The optic will be a Vortex SPR-1301 Spitfire 1x Prism scope. As much as I'd like to have an AimPoint RD sight, red dots and holographic sights don't play nicely with my astigmatism.

In any case, I very much appreciate all the knowledge here and am happy to no longer be a lurker!