Talk:SIG-Sauer MCX

Additional Images

SIG-Sauer MCX SBR with 9" barrel. This one is a pre-production model displayed at SHOT Show 2015, with the front of the upper receiver differing from that of the production version.

SIG-Sauer MCX SBR with suppressor - 5.56x45mm / .300 Blackout

SIG-Sauer MCX VIRTUS SBR with 6.75" barrel, Midwest Industries 6" handguard, SLX762C-QD suppressor and EOTech EXPS3 holographic sight - .300 Blackout

SIG-Sauer MCX-SPEAR, 2019 prototype - 6.8x51mm FURY

SIG-Sauer MCX-SPEAR with 9" barrel

SIG-Sauer MCX-SPEAR in MRGG-S configuration with 20" barrel - 6.5mm Creedmoor

SIG-Sauer MCX Rattler LT with forward assist and 7.75" barrel, pre-production model. As of May 2023, this was the version of the RSAR (Reduced Signature Assault Rifle) adopted by USSOCOM.

ALTRD 10.5" handguard for SIG-Sauer MCX VIRTUS

SIG-Sauer MCX Low Visibility Assault Weapon (LVAW) aka "Black Mamba" - .300 AAC Blackout

Discussion

MCX upper on AR lower

Can an MCX upper be safely fired on a standard AR carbine lower without using the folding stock adapter? I.E., if I pulled the upper off my 6920 and put an MCX upper on, it won't explode or something on the first round? I was reading a thread on AR15.com about this "hybrid" combination where one user spoke against doing so without elaborating, but since the thread has been dead for two years, I doubt he's coming back to do so any time soon. Spartan198 (talk) 19:50, 10 May 2021 (EDT)

https://www.thetruthaboutguns.com/gear-review-sig-sauer-mcx-stock-adapter-for-ar-15-receivers/ This appears to show a regular AR lower with MCX upper, appears to work as normal other than the regular AR buffer assembly doesn't do anything - as pointed out in the article too, the MCX has a taller receiver, but that rear section is already covered, just abruptly without an adapter.--AgentGumby (talk) 08:07, 11 May 2021 (EDT)

Makes me wonder why the AR15.com poster left such an ominous warning. Spartan198 (talk) 11:57, 11 May 2021 (EDT)

Coming back to this, I suspect it must be due to gas blowing back through the open gap - probably since anyone doing this would also be using a suppressor. Guess its best to use the stock adapter or have some proper face protection.--AgentGumby (talk) 03:05, 13 November 2022 (UTC)

New generation MCX

A third generation version of the MCX series is coming soon, as seen here (EDIT: video no longer available) and here. The weapon is lighter, and comes with a new handguard and latch system; it can now more easily use 7.62x39mm ammunition. The rear of the upper receiver also looks somewhat similar to the 1st gen MCX (as opposed to the 2nd gen VIRTUS). Some 3rd gen MCXes were previously displayed at DSEI 2021 (these can be seen at the end of this post), albeit with low profile deflectors like the MCX Rattler, instead of forward assists. There's also a newer version of the Rattler here. --Ultimate94ninja (talk) 10:03, 16 April 2022 (EDT)

It's in production now. It's called the MCX-SPEAR LT, and unlike the prototypes linked above, it has an ambi bolt catch. --Ultimate94ninja (talk) 16:54, 19 September 2022 (UTC)

And now the Rattler LT has been released. --Ultimate94ninja (talk) 21:11, 17 November 2023 (UTC)

Spear and Spear LT barrel lengths

SIG's website only shows 13" and 16" options for the Spear and 9", 11.5", and 16" options for the Spear LT. What's the source on the Spear's 9" and Spear LT's 10.5" and 14.5" options? Spartan198 (talk) 00:12, 16 August 2023 (UTC)

Regarding the 9" Spear and the 14.5" Spear LT, they are military/LE versions shown in the following catalogs: [1] and [2]. When the Raptor (the shorter-barreled version of the Spear) was announced two years ago, some sources were claiming that it has an 8" barrel, but the newer links that I just provided indicate 9 – rightfully, since it does look like a 9" barrel rather than 8. As for the 10.5" barrel on the LT, it was seen on this prototype, though I don't know if it's being used on current production models.

There is also another barrel option for the LT shown here. The length isn't specified, but from the looks of it, it could be something around 12.5"

--Ultimate94ninja (talk) 18:56, 16 August 2023 (UTC)

Here's another look at the 10.5" version. It's been recently seen in Delta Force hands. There were reports about them planning to adopt the 10.5" LT (and possibly 14.5", or is it just a rumor?) as a successor to the HK416, under the designation CSAW (Close Support Assault Weapon). I'm not sure about its current status. --Ultimate94ninja (talk) 22:22, 9 December 2023 (UTC)

On another note, I don't think that the MCX was developed from the LVAW (like you added in the page), but the other way around. These are the early MCX prototypes introduced in 2013 (apparently known as HALO at some point), and the MCX LVAW variant was unveiled a year later. --Ultimate94ninja (talk) 20:51, 7 September 2023 (UTC)

Oh, I see. That Defense Review article on the LVAW was the earliest MCX article I'd seen before. And I was going off a Delta/CAG picture thread on a site I can't remember the name of where someone referred to as "MCX Gen 0". I'll move the LVAW pic to the talk page. Spartan198 (talk) 02:26, 18 January 2024 (UTC)