Sig MCX Gen 3 Updates

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Minuteman
Oct 27, 2021
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Sig is releasing Gen 3 updates of the MCX platform:

  1. AR drop in trigger
  2. 1 lb lighter
  3. Slimmer handguard
  4. 7.62 version coming soon

Some photos:
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I was lucky to get a Sig Spear (waiting for my eform) and i have 2 sig gen 2 , very nice guns. Sig revised both the MCX and MPX to gen 3.

video of mcx 3 and spear here



mpx 3
 
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and still no barrel conversions available.
you means for the MPX? Yeah i am still pissed about that .. and pissed when they had that shroud the atf didnt approve (but impact guns still took my deposit and still havent given it back). I have a Gen 1 Mpx cut down to sbr 4" with a octane can on it and it has never failed. Have a gen 2 upper i never had to get out the box.
 
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I was lucky to get a 300 blackout conversion kit for my 5.56 Gen 2 MCX Virtus. It has been impossible to buy one from SIG for years now. It is such a great concept but for some reason SIG just stopped manufacturing these conversion kits.
 
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Sig couldn't fix the MPX in the first 37 iterations they refused to assign a "gen" number to, not sure I trust them to fix it this time :) They have great marketing though, too bad the execution of the actual product doesn't get that much attention.

The MPX had a minor but meaningful upgrade from Gen 1 to Gen 2 (gas port opened up). Gen 2 was great except for the trigger. It was hot garbage, but a Geissele trigger cleaned that right up. Now it‘s one of the best sub guns out there.

As for the MCX, can’t wait to pick up a Gen 3. Passed on the Gen 2 due to other priorities, but will try to pick up the new model.
 
Makes me wonder how they shaved off the weight. The wall thickness on the uppers are pretty pronounced since they're using 6061-T6 extrusions, makes me think they could save some weight if they went with forged 7075 for thinner walls. My guess is the NGSW is 7075 based off what the rep is saying about changes that needed to be made for the higher pressure cartridge.
 
The MPX had a minor but meaningful upgrade from Gen 1 to Gen 2 (gas port opened up). Gen 2 was great except for the trigger. It was hot garbage, but a Geissele trigger cleaned that right up. Now it‘s one of the best sub guns out there.

As for the MCX, can’t wait to pick up a Gen 3. Passed on the Gen 2 due to other priorities, but will try to pick up the new model.
I'd disagree, the MPX in Gen 2 had lots of issues and updates. Broken firing pins and firing pin springs in early Gen 2's that required a new bolt/firing pin design, several chamber ramp iterations to improve feeding. They had to change the barrel retaining bolts from individual bolts to a 1 piece design, because people were stripping the upper receiver recessions for them (factory loctite required too much torque to break them free and rounded out the flats in the upper that held the bolts). They had to change the bolt cam pin to the new "bowtie" version because it was badly gouging uppers (to be fair some of those were probably users putting it in backwards, though I'd make the case that a bolt cam pin that can't be installed either way like basically every AR is asking for user issues). They had gas issues and had to go from a variable gas tappet to a fixed open plug. They had extractor issues, with early Gen 2's coming with an o-ring, later versions did not, people report both working well, some found extraction issues were due to the extractor spring being installed upside down. They changed the design of the recoil spring plate due to failures. They also had lots of issues with the extractors coming loose, and also cam plates.

That's just the things I know about.....

I'd be willing to bet that all of these "Gen 2" changes were one reason why especially early in the Gen 2 MPX lots of people were having tons of issues, while others were having none. Sig took so much bad press for bringing out the Gen 2 less than a year after the Gen 1, they learned their lesson, now they won't attach "Gen X" to most guns.
 
I'd disagree, the MPX in Gen 2 had lots of issues and updates. Broken firing pins and firing pin springs in early Gen 2's that required a new bolt/firing pin design, several chamber ramp iterations to improve feeding. They had to change the barrel retaining bolts from individual bolts to a 1 piece design, because people were stripping the upper receiver recessions for them (factory loctite required too much torque to break them free and rounded out the flats in the upper that held the bolts). They had to change the bolt cam pin to the new "bowtie" version because it was badly gouging uppers (to be fair some of those were probably users putting it in backwards, though I'd make the case that a bolt cam pin that can't be installed either way like basically every AR is asking for user issues). They had gas issues and had to go from a variable gas tappet to a fixed open plug. They had extractor issues, with early Gen 2's coming with an o-ring, later versions did not, people report both working well, some found extraction issues were due to the extractor spring being installed upside down. They changed the design of the recoil spring plate due to failures. They also had lots of issues with the extractors coming loose, and also cam plates.

That's just the things I know about.....

I'd be willing to bet that all of these "Gen 2" changes were one reason why especially early in the Gen 2 MPX lots of people were having tons of issues, while others were having none. Sig took so much bad press for bringing out the Gen 2 less than a year after the Gen 1, they learned their lesson, now they won't attach "Gen X" to most guns.

I have an early Gen 2 (8”). The thing runs like a sowing machine. Maybe I’m lucky but I’ve put 1000+ rounds through it and the thing just runs, suppressed and unsuppressed.

”They had to change the barrel retaining bolts from individual bolts to a 1 piece design, because people were stripping the upper receiver recessions for them”

That looks to be a dumb user issue. How you would do that using the proper spec’ed torque for those, I have no idea. I‘ve taken those off countless times, and no issues.

I think the other issues you mentioned are minor or rare cases. Sig actually updated the firing pin design within the Gen 2 line, but said if you had the older version (no spring), it was still fine. Like I mentioned, never experienced a broken firing pin with mine, but I have a spare one in the event something crazy happens.

If I had to buy a Gen 2 MPX over again, I would. I’m actually happy I bought the 8” version, because Sig no longer produces that model.
 
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My Gen 1 MPX 8 inch is one of my favorite guns to shoot and is my primary bedside HD firearm. Yes, I've made countless upgrades to it . . . but it has easily 2000+ rounds through it and not one issue. This (and a Shadow 2) are the guns I hand to new shooters at the end of some range time for them to end the day with big smiles and confidence in themselves. Big fan and I hope the MCX update magically increases inventory as well.
 
I was lucky to get a 300 blackout conversion kit for my 5.56 Gen 2 MCX Virtus. It has been impossible to buy one from SIG for years now. It is such a great concept but for some reason SIG just stopped manufacturing these conversion kits.
Yeah, this is really the only thing that is holding me back from picking up a MCX. Maybe I have been spoiled by shooting LMT's for years, but the lack of spare barrels sort of puts me off the platform as the platform is marketed as this cool modular concept that can be configured in over 500 configurations, but they only have like two or three barrel options.

Maybe the gen 3 will address this stuff
 
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I had a talk with customer service about the MCX Gen3 their impression is this version likely will not be launched until next year. The model in the videos is still a prototype, features like weight, compatibility, and features aren’t yet set in stone.
 
Still as gassy as Auschwitz? Too soon?
If you ask an MPX owner... why no, not at all, I have no idea what you are talking about, the gun is amazing, and despite it's full auto cyclic rate being 1150rpm and it beats the shit out of triggers - of course it has a the action stays closed for the entire dwell time and isn't gassy! My Gun and My Ammo and My Can is perfect!

... But if you ask anyone not financially invested in it... they can tell you in about two suppressed shots.

If they didn't fuck up the cyclic rate / dwell time / gas on this gun, it would have absolutely dominated the MP5 and every other PCC market. People don't actually care about $70 mags because look at the fucking MP5. The hush part of this gun is that it's an aggressive little asshole when suppressed; that it's light reciprocating mass and super fast action and quick cyclic rate are desirable for competition but utterly blow suppressed.
 
Same shit different day.

The only people who buy this junk don't know any better.

Its not like Sig hasn't been doing the SAME FUCKING SHIT for 20 years.

Thank god for idiots or they would have went bankrupt a long time ago.
 
If you ask an MPX owner... why no, not at all, I have no idea what you are talking about, the gun is amazing, and despite it's full auto cyclic rate being 1150rpm and it beats the shit out of triggers - of course it has a the action stays closed for the entire dwell time and isn't gassy! My Gun and My Ammo and My Can is perfect!

... But if you ask anyone not financially invested in it... they can tell you in about two suppressed shots.

If they didn't fuck up the cyclic rate / dwell time / gas on this gun, it would have absolutely dominated the MP5 and every other PCC market. People don't actually care about $70 mags because look at the fucking MP5. The hush part of this gun is that it's an aggressive little asshole when suppressed; that it's light reciprocating mass and super fast action and quick cyclic rate are desirable for competition but utterly blow suppressed.

I’ve sold all 3 of mine so I’m no longer financially invested, and I can tell you that you’re wrong. I also shot all 3 of them suppressed. It’s the best PCC on the market by far.
 
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Jesus Sig is a fucking dumpster fire. My department are issued these with cans. Can’t shoot them with out glasses due to the horrendous gas blowback hitting you in the face. And now a new Gen already. It’s amazing they are as successful as they are as a company. Their business model seems to be let the consumer be beta testers and go from there…
 
Jesus Sig is a fucking dumpster fire. My department are issued these with cans. Can’t shoot them with out glasses due to the horrendous gas blowback hitting you in the face. And now a new Gen already. It’s amazing they are as successful as they are as a company. Their business model seems to be let the consumer be beta testers and go from there…

Are you talking about the MCX Rattler specifically? Yeah, those are horribly gassy. Only suppressor that should be used with those are flow through suppressors.
 
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Jesus Sig is a fucking dumpster fire. My department are issued these with cans. Can’t shoot them with out glasses due to the horrendous gas blowback hitting you in the face. And now a new Gen already. It’s amazing they are as successful as they are as a company. Their business model seems to be let the consumer be beta testers and go from there…
What are you guys installing those sig cans on?
 
It’s the MCX virtus, select fire in 5.56. Gemtech shield cans. Flow through cans would have been the ticket, but I’m not the one who gets to pick.
 
My MCX Virtus 16” 556 is only gassy with a Radian CH and it was miserable with that thing for some reason. With the factory CH it’s very low gas. That’s running an AAC can too.
 

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My MCX Virtus 16” 556 is only gassy with a Radian CH and it was miserable with that thing for some reason. With the factory CH it’s very low gas. That’s running an AAC can too.
If you’re relying on the charging handle to fix your problem, the gun wasn’t designed to run well suppressed from the start. A PWS upper is likely a better suppressor host than most of the current sig lineup.
 
i've had 2 MCX virtus and sold one. the other is going to get sold soon too. great rifles, super smooth shooting...so much so i sometimes dont notice its locked back and that kinda bothers me.

couple thousand trouble free rounds thru each but they are nose heavy pigs and sig is constantly making changes. not something i want to chase.
 
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I have a lot of time with a Virtus with a 13.5" 5.56 barrel now. I've used a Sandman S and a Hybrid on it with no blowback to the shooter and I've done some mag dumps to try and get it to gas me out. Poor suppressor choice will make almost any rifle suck tho and these cans are known to be low blowback. However, I haven't shot any other versions to compare it to. Mine is super smooth shooting and the only real negative is that it is heavier than an equivalent AR15 and of course Sig.

If you’re relying on the charging handle to fix your problem, the gun wasn’t designed to run well suppressed from the start. A PWS upper is likely a better suppressor host than most of the current sig lineup.
I had a PWS upper and sold it after acquiring the Virtus as it was worse in nearly every way, about as heavy and blowback between the two was a negligible difference. Compared to a similar length Geissele upper, the PWS was heavier, either over gassed or wouldn't reliably cycle depending on gas setting (tried several buffers), less accurate and really performed no different gas BB wise.
 
I have a lot of time with a Virtus with a 13.5" 5.56 barrel now. I've used a Sandman S and a Hybrid on it with no blowback to the shooter and I've done some mag dumps to try and get it to gas me out. Poor suppressor choice will make almost any rifle suck tho and these cans are known to be low blowback. However, I haven't shot any other versions to compare it to. Mine is super smooth shooting and the only real negative is that it is heavier than an equivalent AR15 and of course Sig.


I had a PWS upper and sold it after acquiring the Virtus as it was worse in nearly every way, about as heavy and blowback between the two was a negligible difference. Compared to a similar length Geissele upper, the PWS was heavier, either over gassed or wouldn't reliably cycle depending on gas setting (tried several buffers), less accurate and really performed no different gas BB wise.
Sounds like you had a defective gas block or something. The PWS can switch between unsuppressed and suppressed settings. Something No AR can do aside from a switch block or adjustable gas block which wears down over time. My PWS is more accurate than my centurion arms and BCM barrels. Gas BB on the PWS is much less than a DI gun aside from possibly a extreme reduced gas port which won’t run unsuppressed so no merit in even comparing them really.

Curious as to how it was “worse in every way” when you thereafter state the PWS is lighter and has essentially the same gas back as the virtus… sounds like the PWS was better so I’m a bit confused and curious to hear more on your experience.
 
I have an 11.5 Virtus and run it with a Sandman S and have no problems with gas in the face. when you run it on the suppressed/low gas setting it shoots super soft, accurate and clean. I liked it enough that I form 1'd it a couple months ago, so I'm all in with it. I had a chance to sell it during the pandemic for more than twice what I paid for it and these things were unobtanium. I didn't do it cause Its my favorite .556 rifle to shoot.

If you're having gas issues, then you have the wrong cans or something is wrong. Its a piston gun, the only way to get gas in the face is back down the barrel, so its entirely on the suppressor, not the gun at all. A suppressor that gives you gas on the Virtus, will do the same on any other gun of similar barrel length.
 
all you guys complaining about gas to the face should try shooting left handed sometime, then get back on what gas to the face feels like. lol

as a lefty myself, its a shitty deal. every once in awhile i’ll shoot right just to remind myself how nice it could be.

i always assumed gas blow back was just a function of the suppressor. i hardly get any gas shooting right handed. thats with 3 different style cans too.
 
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The more information comes out the more I’m realizing all of the “features” in the Virtus I thought were steps backwards, were in fact steps backwards: heavier profile barrel, heavier handguard without improving contact points, BCG changes making it incompatible with standard bolts and AR-15 triggers. None of these were helpful enough to even last a single generational update and all of them are being reversed.

If I had to sum-up the Gen3:
-MCX G1 Upper with Virtus length top rail
-MCX G1 Barrel Profile with Virtus Bolt/Barrel Extension
-MCX G1 BCG Assembly
-Midwest Industries Handguard
-ADM UIC Lower

Might was well have just skipped the Virtus step and got on with making a good rifle better years ago.
 
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