The Ultimate Firearms Destination for the Gun Lifestyle

Live Blogging the MCX Rattler Release

At RECOIL, we review every product fairly and without bias. Making a purchase through one of our links may earn us a small commission, and helps support independent gun reviews. Learn More

Earlier this morning we had the opportunity to video conference directly with SIG Sauer HQ about the release of two new MCX variants: the Virtus and the Rattler. Listed below is all the information we received on the new carbines. [Editorial notes in brackets.]


Both the Virtus and Rattler are based on the short-stroke MCX platform, which was originally designed based on product requests from military Special Operations. These guns are designed and tested to run 20,000 rounds before the first required parts replacement. The multi-position gas valve system allow you to optimize the rifle for suppressed function.

There are two calibers available in the MCX system: 5.56mm and .300 Blackout. Between the two calibers, there are five different barrel lengths available. Currently the Virtus/MCX line has seven stock options, with an eighth coming on the Rattler's release. Stock selection includes: fixed adjustable, folding non-adjustable, collapsible and telescoping folder. These are all available on SIG's website now. The new stock configuration featured on the Rattler will be out in the near future. [While we didn't get a great look at the Rattler stock, it appears to be a fixed-length side folder of different length and configuration from what we've seen on the legacy MCX.]

Speaking of modularity, there are also multiple handguard options available – a “slim” and an “SD” version. The latter has a 2.6″ outer diameter and is designed to house SIG suppressors. [This style of handguard is becoming incredibly popular to create suppressed SBRs without losing “rail-estate” on the handguard.]

Virtus maintain's the MCX's full ambi controls, with some enhancement to said controls. The Virtus includes SIG's newest trigger, which they are referring to as the match-lite duo trigger. [They didn't spell it for us, so we're guessing on that.] It is a two-stage trigger with a 2.5lb first stage and 2lb second stage. The match-lite duo trigger, as well as all the other furniture and accessories on the Virtus, are designed and produced in-house at SIG. The Virtus also includes a firing pin block to the fire control group, for additional safety.



The Rattler is based on “professional user” requests for a small, low-profile gun with more power than a traditional submachine gun. Overall length of the Rattler when folded is 16″.  Extended length is 23.5″. Users will have full access to all controls with the stock folded, and the gun CAN be fired from the collapsed position. The forward assist was eliminated to make the receiver as narrow as possible specifically to prevent snagging when deploying from a bag. It's diminutive size was critical to the design process – SIG says it is the same size as an MP-5, and smaller than some other subguns on the market right now. [We'll be sure to do some side-by-side when we get our hands on one of these.]

The Rattler will be available in both .300 Blackout and 5.56mm. The .300 system will have a two-position gas block with positions for suppressed and unsuppressed fire. The 5.56mm version will have a gas block that uses a plug system and will NOT be able to be run suppressed. [Running a can creates both additional heat and additional back pressure. Trying to pop a can on the 5.56mm gun, with the muzzle so close to the gas block, could drive the temperature and pressure curves to unsafe levels.]

Rattler will be available in two configurations: an SBR and a PSB (pistol-stabilizing brace) version. The SBR will be available to the commercial market for those who wish to process their NFA paperwork.

The Rattler upper was purposely redesigned to reach their size requirement of a 5.5″ barrel, which is over an inch shorter than any of the barrels currently available for the MCX. Due to this re-design, there are some specifics when it comes to compatibility. Please see all bullet points below for the full scoop [as we have it right now] on compatibility between the MCX, the Virtus and the Rattler.


Rattler barrels are not cross-compatible with Virtus or MCX barrels. Calibers may be swapped within the Rattler platform.

Virtus barrels are not immediately compatible with legacy MCX guns. Conversion kits will be made available.

Any MCX stock will work with the Virtus and the Rattler.

The Rattler upper will work on any MCX lower.

The Rattler lower will run with any M4 upper, once the buffer tube is installed.

Third-party suppressor compatibility is the same as with previous versions of the MCX. No answer on whether they will warranty the Rattler if third-party suppressors are used.

SIG says they DO intend to support legacy MCX platforms.


The .300 Blackout version of the Rattler is scheduled to start shipping next week [August 28th], while the 5.56mm version is expected to start going out the door in November. The staggered timeline comes from an increased level of demand for the .300 version from both professional end users and the commercial market. The MSRP on the MCX Rattler is $2,799.

This is everything we have on SIG's newest carbine offerings at the moment. Stay tuned to RECOIL and RECOILweb as we dive deeper into the story and get our hands on one.

You can watch the complete stream here:

Enter Your E-Mail to Receieve a Free 50-Target Pack from RECOIL!

NEXT STEP: Download Your Free Target Pack from RECOIL

For years, RECOIL magazine has treated its readers to a full-size (sometimes full color!) shooting target tucked into each big issue. Now we've compiled over 50 of our most popular targets into this one digital PDF download. From handgun drills to AR-15 practice, these 50+ targets have you covered. Print off as many as you like (ammo not included).

Get your pack of 50 Print-at-Home targets when you subscribe to the RECOIL email newsletter. We'll send you weekly updates on guns, gear, industry news, and special offers from leading manufacturers - your guide to the firearms lifestyle.

You want this. Trust Us.

Add a comment

Your email address will not be published. Required fields are marked *

Subscribe to the Free