I have never been a ar15 guy but the left is pissin me off. So I went looking at ar's today and ran across one at a lgs marked mcx/400 hybrid. Any body know anything about these? Looks to be just what it says a mcx upper on a 400 lower. It's new in box and came from sig that way. My concern is that it may have been a precursor to the actual mcx and has the earliest mcx upper, meaning all the problems that came with them.

Pointless in my opinion. The MCX lower is much more versatile than the M400 lower when paired with the MCX's piston. Get one or the other.

Thanks the more I think about it, seems like a bastard best to stay away from.

One motivation I've heard for getting the hybrid is it's cheaper than what Sig will sell you just an MCX upper for.

Also if you already have a AR lower that's SBR'd etc. and want to put an MCX upper on it, you need the AR lower adapter, and from what I hear Sig is refusing to sell them to people, or at least they've been on backorder for a year +. Sig is most likely using all of them to make these hybrid guns to get rid of legacy MCX uppers and poor selling 400 lowers.

So there are cases where it can be an advantage.

Controls wise the only benefit I see to the MCX lower is it comes with an ambi mag release.

DaBigBR: how is the MCX lower more versatile with the MCX piston upper? I'm not saying your wrong I'm just curious.

What are the differences between the original MCX lower and the MCX Virtus lower? I recall that the Virtus has the match trigger. Any other external or internal changes?

SIG is throwing together whatever parts they have, maybe???

quote:

Originally posted by RHINOWSO:
SIG is throwing together whatever parts they have, maybe???

We've seen it before, that's what leads me to think this is probably the case.

quote:

Originally posted by RHINOWSO:
SIG is throwing together whatever parts they have, maybe???

"Parts is parts"

Some may know of this classic Wendy's commercial.

Don't walk away Quickly it's a tar bear.
I say this from experience. My work place decided to put together a abortion rifle again. We had sig 400 complete rifles. Military lowers 16 inch flat top hunter gas block rail no sights. That someone ordered Read an Idiot.
So They decided to make some shorty's and use them instead of buying a barrel or 400 short upper. mcx adaptors were made in batches once a year . Regardless the mcx has a grove in lower for carrier to fit in and work. The adaptor does not and will crunch/ erupt springs from receiver or seize.
We told them it used a different operating system and would not be reliable but egh some have to see to realize. Ended up buying complete guns which once broke in work okay so far. Buyer beware good luck.