Sig MPX ... ?

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Sig MPX ... ?

Post by TROOPER »

Sorry for the misleading title, but the thrust of my question is this: assume for a moment that the MPX-C variant became available for sale... is there some advantage to going that route as opposed to purchasing the Sig MPX-P and SBR'ing it? I suppose what I'm really asking is if the level of suppression for Sig's version of an integral would be significantly quieter than a top-tier silencer screwed on to the MPX-P.

The way I understand it, if a person get's the MPX-P, then they'll need to pay the $200 to attach a buttstock. OR... they can buy the MPX-C (assuming availability) and pay the $200 to put on the Sig "sleeve" which then completes the silencer package.

The downsides to the MPX-C (again, assuming that it becomes available) is that you're relegated to only that one particular silencer, that and the fact that it basically becomes a package deal in the event of selling it. I also have concerns about the level of suppression of what is basically a permanently mounted mono-core. Wouldn't conical baffles do better? Or is the benefit of using a threaded suppressor offset by the fact that the permanently attached monocore is an integral?

What are the downsides of SBR'ing the "P" version? How difficult is it to sell it in the future? Can you simply take the buttstock off, call it a pistol, then sell it as such? How significant is it that any suppression would necessarily be a thread-on as opposed to an integral? I realize that integrals are typically quieter, all-things-considered, but that is a flat-baffle stack... so is it still quieter?

Thoughts?

I only ask because I'm seeing reports / rumors that the MPX-P is available, although somewhat difficult to find. I've been trying to compare it to the CZ Scorpion Evo-3, but that is a blow-back system, and after paying the SBR to put a butt-stock on it, it still doesn't seem as though it would be particularly quiet. Or at least the Youtube videos I've seen of a suppressed CZ Scorpion show what appears to be a significant amount of gas exiting the breech. I assume that some sound must accompany that expulsion.

Thoughts on that as well?

Thanks in advance.

Oh yes, last question, are there any updates to the ATF vs Sig MPX-C issue?
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Re: Sig MPX ... ?

Post by TROOPER »

I went ahead and ordered it. Of course, it isn't in-stock, so there's plenty of time to back out of the deal. However, for now, it is ordered.

Side note, after further internet'ing I discovered that the MPX-P seems to be available ONLY in an 8-inch barrel configuration. I see indications on the Sig website that the barrel lengths are also 6.5 and 4.5 inch, but they don't appear to be options for civilian -- IE, non-LE/Military. I do wonder if the 4.5 inch barrel by itself can be purchased, but frankly, even if it isn't, I can live with an 8-inch'er.
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Re: Sig MPX ... ?

Post by lcambre »

My understanding is that the 6.5" version is no longer planned. The 4.5 inch (maybe 4) one should be released later this year. Also SBR versions and a 16" version. Sig really needs to clean up their web sites now that they have finally gotten this into production.
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Re: Sig MPX ... ?

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Agreed. Hopefully I can purchase the 4.5 barrel as a part later. I expect to pony up a couple-hundred dollars for that if it is even possible.

... but then again, perhaps simply purchasing a longer hand-guard is the way to go, so that the silencer only pokes out a little bit. I really appreciate how little 9mm is affected by barrel lengths... or at least the barrel lengths we're talking about with this MPX.
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Re: Sig MPX ... ?

Post by Dieseljay »

TROOPER wrote:Agreed. Hopefully I can purchase the 4.5 barrel as a part later. I expect to pony up a couple-hundred dollars for that if it is even possible.

... but then again, perhaps simply purchasing a longer hand-guard is the way to go, so that the silencer only pokes out a little bit. I really appreciate how little 9mm is affected by barrel lengths... or at least the barrel lengths we're talking about with this MPX.

Ok so after talking with a few of the sig store sales people. Magazines are on pre order / back order of 3-4 weeks. Telescoping stock is on back order 4-8 weeks. A3 stock is around 4 weeks out and you can pre order it for ~190 depending on which rep you have and if you apply your 20% discount.

The 4.5".... They conservatively say late summer. (My opinion is you can pre order it at that time but it won't be shipped to mid to late 4th quarter).

Now I already have a MPX-psb.. The rail on this will allow for anything but an opsery to fit under the longer rail. With the 8" barrel just the mount fits under the rail but the suppressor sticks out.

One consideration about the mpx-c with the break is that it might have less back pressure than the standard p with an after market can. I highly doubt it will put preform the octane or tirrant 9(t9 was a touch less noisy with 158's Focchi). One problem with after market cans is that currently with my octane 9mm and another's tirrant 9mm are over gasses and Sig tech won't tell anyone how to adjust it. I can't figure out how To adjust this myself.... Maybe someone can figure that out. But shooting this thing lefty suppressed it peppers pretty good.

I can post pics if you have a barrel/suppressor clearance question.


As for noise level I can only give my ears evaluation. Action noise is less than an ar but more than a sig 226. The noise level of the fired round in its over gassed state sounds very close to a 226. I was Surprised how quiet this thing is.

Also I thought SiG was going to resume next month the law suit against the AFT. (Rumor).
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Re: Sig MPX ... ?

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So apparently the MPX-P will be in my possession on Wednesday, May 13th. Obviously I can't attach a buttstock until the firearm is appropriately classified as an SBR by the ATF... which gives me several months to work with. Still, I don't know how to Google the appropriate buttstocks for this firearm. I see plain-as-day that there is a picatinny rail on the rear of the pistol, with a small hole bored through in order to facilitate a pin of some sort. What I don't understand is the mechanism for attaching a 'standard' buttstock -- something off of an ordinary AR -- onto this firearm. Do I need some sort of adapter from Sig? Or is there a small market of picatinny-mounted buttstocks that I don't know about?

Also, the Sig website itself is somewhat limited in parts for this gun. It's possible that I'm merely inadequate at searching, but it appears that right now there is only a single "MPX" matt-slash-over-sized mouse-pad when I go to find MPX parts on the Sig website. Specifically, I'd like to acquire a longer hand-guard than what is on this one, but the way the hand-guard meshes with the upper leads me to believe that it is proprietary. Any suggestions on that front?
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Re: Sig MPX ... ?

Post by Dieseljay »

Ok I don't know whats the length for the mpx-p and not psb version. But yes the hand guard is very proprietary. I beleive they do no have any new handgaurds planned other than shorter ones for resale. The site doesn't show anything right now and won't for some time. If you call customer service after registering the warrenty you will get a 20% off discount. This will allow you to buy 3x 30 rnd magazines.

At that time you can ask them for a telescoping stock which is 190~ with the 20% off. However this will be a pre order. (You won't get it for months which should give you time to get the sbr done. Ps telescoping stock is the mp5 style collapsible stock.)

They have an A3 style but I don't know the part number for it.

Also depending on who you talk to they may not say they have either of the above listed items.

Next up. Barrels 4"~4.5" won't be around to later this year (maybe 4th quarter).

As for the but stock.... I have yet to find any adapters other than sigs (which you can only pre order) if you have the PSB model you can unscrew the pistol tube and attach your own buffer tube.
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Re: Sig MPX ... ?

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Ok. The area that was confusing to me was that I can't seem to find the specific parts listed on the Sig website. I can't tell if my searching skills are weak, or if it's just a matter of an out-of-date or incomplete website. So calling them should take care of that? Great.

Side-note: the UPS estimation of delivery was off by a day. Now I'm expecting it Thursday the 14th.

Which stock do you recommend? Obviously there are a lot of subtle variations amongst the AR 'buffer-tube' stocks, so my question is more broad; do you think the "MP5" style is better for this firearm? Or go ahead and get the tube which will allow a wider range of options?
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Re: Sig MPX ... ?

Post by Dieseljay »

TROOPER wrote:Ok. The area that was confusing to me was that I can't seem to find the specific parts listed on the Sig website. I can't tell if my searching skills are weak, or if it's just a matter of an out-of-date or incomplete website. So calling them should take care of that? Great.

Side-note: the UPS estimation of delivery was off by a day. Now I'm expecting it Thursday the 14th.

Which stock do you recommend? Obviously there are a lot of subtle variations amongst the AR 'buffer-tube' stocks, so my question is more broad; do you think the "MP5" style is better for this firearm? Or go ahead and get the tube which will allow a wider range of options?

I can't recommend a stock. Thats a personal preference.

Also website now has magazines.
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Re: Sig MPX ... ?

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Any updates? How does it run suppressed? Over gassed?
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Re: Sig MPX ... ?

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Well... this is going to sound banana-sandwich, but I haven't shot it yet. Not even once.

Here are some cursory observations and a tentative idea. First, the gun is heavier than it seems like it would be, but the trigger pull (dry-firing) is very crisp, although a touch heavy... and a very short reset.

Second, the vast majority of controls are ambi, but with caveats. For example, the magazine release is certainly ambidextrous... the bolt-release is ambidextrous... but the bolt-hold-open is geared for a right-hander. No worries, I don't consider that an 'operational' control. Also, the safety is ambidextrous... BUT... but it isn't the same length on both sides. It's right-hand favored. Therefore, while it does have left-hand access, the lever is considerably shorter -- presumably to avoid digging into the hand of a right-handed shooter -- and it's a little harder to flip with a shorter lever arm.

Also, the rail is uniquely interesting in that it attempts to be a monolithic upper.. and with the way the top rail becomes side rails, it basically does it, while simultaneously being modular out of deference to future variations of this gun.

I haven't done anything with the barrel yet. It's 8 inches... and just barely peeks out of the hand-guard. I figure to cut it down to 4 or 4.5 (undecided), and have it threaded. I hear some people talking (internet forums) about simply buying the 4.5 barrel when Sig releases it, but I don't know what that would cost... AND... it'd still be threaded 13.5 L, which means that I'd have to buy another booster and deal with the hassle of different boosters for different guns. Thanks, but no thanks.

I have the pistol version, and I'm in no rush to shoot it because I'll be filing the Form 1 for an SBR -- literally tomorrow -- and waiting for a butt-stock.

.. which is its own problem, because the internet hasn't been very forthcoming on information that I'd like. Specifically, there are three different butt-stocks planned for release: an "MP5-style-collapsible", a slender, non-telescoping side-folder, and a classic type "buffer-tube" where the end-user chooses their own butt-stock from among the seventy-six trillion currently on the market. I rather want the MP5-style, twin-rail collapsible (~$200 from Sig), but I don't know what the Length-of-pull (LOP) is. If the LOP isn't adequate as-is, and/or extra pads cannot be added to add to the LOP, then that way is a no-go for me. Unfortunately, the internet hasn't yielded adequate information on that topic, so I can't even start the process of making a good decision... and ~$200 is too much for trial-and-error.

Supposedly Sig will start the process of releasing it's butt-stocks mid-to-late summer.. so just a month or so. I hope to have my SBR OK'ed by then, as well as have the appropriate information to make an informed decision.

I'm sorry I don't have additional information. Give me some time and I'll post some pics if you want. The internet already has a pile of pics out there, but they all tend to focus on total-package images, and so they're not always useful. Is there some particular aspect of this firearm that you'd like to know more about?

Oh, another few thoughts: the butt-stocks for this are 100% interchangeable with MCX butt-stocks. So that's good. The MCX gear isn't main-stream yet either, but it gives a wider supply of goods which may help to make it easier for MPX owners. Also I've had a devil of a time doing two things: removing the barrel (still haven't) and getting off the flash-hider (still haven't).

Oh yes (sorry for the meandering post), the 'proposition' I've got.... You asked if it's over-gassed. I don't know from experience, but the internet says that it is, and that this problem is exacerbated by a silencer, and that the valve is auto-regulated, and not end-user adjustable. I don't know beans about how these things work because I've never owned an AR. But I wonder if I can't add a relatively small tube OVER the valve, and extending out the front of the hand-guard. This won't help with the over-gassing aspect, but will it vent the excess gas out near the muzzle? Yes? I don't know... because I don't know how these things work. Where does the excess gas go? Out of the ejection port? Or out of the... gas-block? Gas-valve? I don't even know what the heck it's called.

Ah yes... last thought -- the hand-guard seems to be ideally sized to host a silencer. I'll be sure to include some quality pics of that aspect tomorrow. Pistol caliber silencers tend to be relatively narrow in order to avoid over-obscuring the sights. The hand-guard here easily handles something like an Evo-9 (what I have), and conceivable relatively larger cans. Again, I'll be sure to put some pictures of that, as well as use some calipers to get a significantly more detailed report of what to expect on this thing.
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Re: Sig MPX ... ?

Post by cyclone72 »

pics or it never happened
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Re: Sig MPX ... ?

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I'm working on it. It's taking me a hot minute to get my trust pages scanned for the ATF, Form-1 e-forms submission.
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Re: Sig MPX ... ?

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Alright... bear with me. I've done some reviews in the past and I normally like to have a much more refined product than what I'm about to put up here. Still, here are some pics that illustrate some of the key points that I found interesting.

Here is an overall shot.
Image

Here is the lower without the upper, and you can see that this orange plasticky-rubbery thing is installed. I assume it's to cut down on the noise of the cycling by dampening the impact of the metal bolt against the metal stop. I greatly appreciate this since I've tried to monkey around with just such a thing on my blow-back CX4 Storm. Unfortunately the lock-up was supplied directly by the metal-against-metal contact, and so there was just no way (that I could see) to cut down on the offensively loud *CLUNK!* of the bolt shutting.
Image

Here in this picture, you can see that I've partially slide the front hand-guard off enabling you to see how the top-rail and side rails fit together. You can just make out a groove where the hand-guard fits into the upper, as well as small metal pin/rod on the bottom. If you look really sharply, you'll see that there is a semi-curved indenture in that pin which aligns with the pin. Basically, when the upper has both pins in place, that little rod can't slide out. Between that little rod and the grooves milled into the upper, the whole hand-guard / "rail-estate" seems quite firm and immovable. It has multiple contact points to hold it still relative to the upper.
Image

Here is the upper + barrel without the hand-guard. This is an eight-inch barrel, which I've literally, LITERALLY, just asked (and paid) the ATF to have it cut down to 4.5 inches. This barrel is held in by two bolts which take a T-25 Torx to undo. No lie: I literally broke my Torx bit undoing one of them. I suspect the assembly-line-man used an air-wrench to put it in.

This has been a modest point of frustration for me for two reasons. First, I haven't removed the flash hider yet because it's too hard. Not the flash-hider, but my head; I was trying the lefty-loosey-righty-tighty formula for these 13.5 L metric threads.... which surprisingly isn't effective. Second, the barrel should just pull right out once those two retaining bolts are removed, and that's what Youtube has shown before. I haven't been able to "just pull it out", however. That said, a few others have reported a similar problem, and one owner used a wooden dowel rod to tap it out from the chamber side. Brilliant. I'll do the same, I just haven't done it yet.
Image

Ok, last photo here. I completely removed the hand-guard (and the vertical grip since it was preventing the affair from standing straight up on this bench) and dropped my AAC Evo-9 inside of it. This will give you a good idea of what a pistol-silencer looks like inside so that you can see what kind of room you have to work with on this system. I can't thread the silencer on right now because my booster has the 1/2x28 threads. Still, you can see how much room you have to work with, and frankly, I wouldn't be surprised if this get-up encouraged a number of Form 1 silencers given the amount of space a person has to work with in there.
Image

I'm kinda' sorry for the not-well-cropped-and-labeled pics, but it's late and I'm tired and I didn't want folks to wait since it seems there's at least two people watching this thread.

It'll take a while, but after the SBR is approved and I have the barrel threaded for 1/2x28 and I have some good range-time on it, I WILL put up a pic-heavy review.

--------- ETA --------
I said I asked the ATF for permission to cut the barrel.... well, yes-and-no. Yes, I did just ask them for permission to add a buttstock... no, not to cut the barrel. The point I was driving at was that I filed for an SBR. While typing this post I forgot that I was taking a pistol to a rifle, and not a rifle to a shorter-barreled rifle.
Last edited by TROOPER on Sun May 31, 2015 8:45 pm, edited 1 time in total.
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Re: Sig MPX ... ?

Post by TROOPER »

Oh yes -- that IS a Beretta vertical grip on there. I got a little irony out of that.

But that aside, how does the excess gas of an "over-gassed" firearm exit the gun? Not through the muzzle, so is it through the ejection port or through the valve just above the barrel?
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Re: Sig MPX ... ?

Post by seattlite »

Thanks for the pics and write up!!

Will you have to strip the barrel assembly down to just the barrel to get it re-threaded?
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Re: Sig MPX ... ?

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I don't know how to answer your question. I haven't removed the barrel yet.

However... this is what I expect to remove and send off for cutting (still haven't determined WHO to send it to... Adco? Tornado Tech? Gemtech?)

Image

My thinking is this: the cost of cutting and threading this particular barrel is probably cheaper than me buying a new barrel PLUS the cost of a new 13.5L booster for my Evo-9. There's also the hassle of having different boosters. For simplicity, I'd rather have everything the same.

... but I don't know the answer.

That said, I believe the picture I just posted -- taken from a screenshot of Sig Sauer's website -- is exactly what you'd get in the mail if you ordered an 8-inch barrel from Sig.... a barrel + piston.
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Re: Sig MPX ... ?

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I called Sig CS and ordered a sliding butt-stock --- the kind you'd see on an AR --- for ~$300. The CS said it should ship in August... early September at the latest.

I was concerned that if I went with an A3 -- the twin railed slider you see on an MP5 -- that the LOP couldn't be set long enough for my frame. In the pictures above, the indentations in the upper which are made to accomodate the A3 aren't very long. I took that to mean that there was both a finite AND short LOP with that particular setup. The gain is an increased compactness for portability... and while I think that would be 'cool', the reality is that I just won't get much use out of it.
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Re: Sig MPX ... ?

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Niiiiiiiiiiiiiiiiiiiiiiiiiiiiice!
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Re: Sig MPX ... ?

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Modest updates:

Here is a picture of the final product UNTIL the ATF gives the go-ahead for the SBR. I'm told the ATF is a little backed-up at-the-moment since many of the staff take summer vacations. I heard that on the internet, so it must be true.
Image


Here is a picture of the 'exploded view'
Image


Here is a picture focusing on the barrel
Image


My understanding is that the ballistics will be essentially identical to a suppressed GLOCK 19: a four-inch barrel + silencer. 147 should stay subsonic, and since Sig itself is producing a 4-inch version, I'm relatively assured that my own 'special-order-chop-job' should work just fine.

Here is the website of the small company which did my work. I don't recall what they charged, but it was reasonable IMO. The one man I spoke with who did the work was very responsive to email and a single phone-call later. Here's the thing: the work was fantastic, and every aspect of the transaction was just ideal. I don't want to short the man or that company their just dues... it's just that I don't have the specifics of the price or time-table in front of me, and in fact, am only updating this thread because a different ST member sent me a PM asking for information on the MPX. After telling him everything I could, I figured I'd share here as well since it's mostly a cut-and-paste of what I sent the PM fellow. But when I get to the long review of this firearm after the ATF clears the SBR and the Form 4 for the Thompson Machine SG-2, then I'll also sing the praise of Fort Daniels gun-smithing, because they deserve better than the little bit of positive I've said so far.
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Re: Sig MPX ... ?

Post by RJT »

Dammit Trooper, I've been resisting the urge to get one, until I saw yours. Son of a b****!!!!!!! :D
You keep using that word. I do not think it means what you think it means.
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Re: Sig MPX ... ?

Post by YugoRPK »

Just cant convince myself to build a blowback 9mm SBR after that horribly loud AR-15 9mm I had. Maybe if were in .45 but I don't see SIG doing that.Been waiting for the MCX to hit dealer shelves but not having any luck.
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Re: Sig MPX ... ?

Post by jreinke »

TROOPER wrote: Image
Nice AOW ya got there! :shock:
[url=http://militarysignatures.com][img]http://militarysignatures.com/signatures/member1236.png[/img][/url]
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Re: Sig MPX ... ?

Post by TROOPER »

jreinke wrote:
Nice AOW ya got there! :shock:
Yeah... I made an error, realized it, then took the VFG off. What can you do. Although if the ATF is looking at these pictures, I'd just like to point out that they're all photo-shopped.
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Re: Sig MPX ... ?

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Before I got the SBR stamp back on one of my 300 BLK AR-15's I had it configured as a 10.5" "pistol" . Then I added a forward grip and posted a pic. I had people coming out of the woodworks PMing me to take that pic down 'cause I was breaking the law and that Hillary and the storm troopers would be by post haste to stomp my kitty and I was making us all look like a bunch of scofflaws blah blah blah. Then I had to remind them that I was fully in compliance of the law as it was over 26" or whatever the limit is and it was not considered an AOW and was a "firearm" in the eys of the ATF and they could lick my gooch.
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