SIG MCX: When is an AR not an AR?

[Beat Trash]

Get back with us once you've shot it a bit. I'm also curious see how it shoots. Especially once the gun heats up a bit.

[TacticalFun]

Get back with us once you've shot it a bit. I'm also curious see how it shoots. Especially once the gun heats up a bit.

I have about 2500 rounds through my virtus with no issues

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[MSparks909]

I have about 2500 rounds through my virtus with no issues

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What do you think of it compared to a “standard” 16” DI middy?

[TacticalFun]

What do you think of it compared to a “standard” 16” DI middy?

Much heavier but less recoil and very accuarate

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[PNorris]

When I read this thread I hear the following. Wow, the new sig is a great and innovative gun. That, however, was closely followed by, Oh crap the bolt carrier group is very problematic and requires a re-design. Then came, the meat of the thread where sig is trying to make the gun reliable and right. Now, people are starting to say that the gun is good again. Now, I hear of the Virtus being a decent gun. As such, I am not sure where it currently stands. I like the design which is basically a modern day AR 18 / 180, however, is it worth it to buy this gun right now? I always value problem free guns. Is this one of them, or am I headed towards a head ache?

[Aries144]

That's not quite what I'm getting. I'm getting:

They redesigned the carrier assembly to accommodate some .300blk ammo with soft primers, stronger/better interface between carrier and recoil assembly, and add a stronger, longer lasting KAC-style bolt. Then our OP has issues that sound like some kind of overgassing issue with the new carrier. Sig can't get it right even after multiple returns. Sig eventually makes it right and gives OP a new Virtus rifle as compensation.

As leery as I am of any large corporation's willingness to take responsibility for problems with their products, Sig seems to be doing well lately.

I concur that this is functionally a rehash of the AR18. It looks to me that the MCX is potentially better than the AR18 in almost every way. Like the AR18 however, it looks like it would be inferior to the AR15 in environmental testing, considering the large gaps between receiver halves, the large opening under the charging handle, and large opening in the front of the receiver for the oprod.

[Tokarev]

My new Virtus has been running well and I've been enjoying it. Unlike my original MCX, I have used this new rifle in both 223 and 300. My original gun I set up as a Blackout and ran it that way the whole time I owned it.

Is it perfect? No. But if the design parameters are to make a gun that looks, feels and handles mostly like an AR but with some non-AR features (folding stock, modular upper) they have probably done as good a job as possible.

SIG and others are starting to support the rifle with forends and charging handles and some other stuff. That's a good sign.

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[justin_247]

Can somebody who owns an MCX pull out the carrier and weigh it on a postal scale?

For comparison, AR-18 bolt carrier assembly weights, according to this site:
Bolt Mass: 0.050 kg (1.76 oz)
Carrier Mass: 0.302 kg (10.65 oz)

AR-15 bolt carrier assembly weights:
Bolt Mass: 0.057 kg (2.01 oz)
Carrier Mass: 0.267 kg (9.41 oz)

[Aries144]

Mine is a Gen 2 bolt assembly from an 11.5" barrel MCX pistol (not Virtus) with the firing pin safety. Guide rods and recoil springs removed for measurement.

Measurements taken with a kitchen scale.

Firing Pin + FP Spring: 0.01 kg (0.35 oz)

Cam Pin: 0.007 kg (0.24 oz)

Bolt: 0.049 kg (1.72 oz)

Carrier: 0.27 kg (9.52 oz)

Piston: 0.02 kg (0.7 oz)

Recoil Springs: 0.019 kg (0.67 oz)


After all that measuring, I discovered that Alex C. on that other site measured a .300blk MCX and his weight values are different than mine. It's possible that his scale was more accurate or that the difference is because my bolt assembly is the Gen 2 and his possibly the Gen 1.

Since my MCX is new, during this more detailed disassembly I discovered my barrel is chrome-lined, not nitrided. I also discovered that I have the new Virtus-type piston and gas valve design, featuring an AK-like gas piston head and gas rings on the gas valve instead of the piston. Cool.

[justin_247]

Mine is a Gen 2 bolt assembly from an 11.5" barrel MCX pistol (not Virtus) with the firing pin safety. Guide rods and recoil springs removed for measurement.

Measurements taken with a kitchen scale.

Firing Pin + FP Spring: 0.01 kg (0.35 oz)

Cam Pin: 0.007 kg (0.24 oz)

Bolt: 0.049 kg (1.72 oz)

Carrier: 0.27 kg (9.52 oz)

Piston: 0.02 kg (0.7 oz)

Recoil Springs: 0.019 kg (0.67 oz)


After all that measuring, I discovered that Alex C. on that other site measured a .300blk MCX and his weight values are different than mine. It's possible that his scale was more accurate or that the difference is because my bolt assembly is the Gen 2 and his possibly the Gen 1.

Since my MCX is new, during this more detailed disassembly I discovered my barrel is chrome-lined, not nitrided. I also discovered that I have the new Virtus-type piston and gas valve design, featuring an AK-like gas piston head and gas rings on the gas valve instead of the piston. Cool.

Thank you!