The folding pistol brace that the MCX ships with...is it just the SIG folding knuckle with a pistol "buffer tube" screwed in, or is it a single folding-adapter-brace unit?

In other words, if you get an MCX pistol and SBR it, can you just put a standard tube on their without buying another folding knuckle adapter?

No, the MCX has a piston-based gas system. There is no buffer tube. There is a short rail system on the back of the MCX where you can attach different stocks.

Here is the SIG webpage showing some of their stocks on offer for the MCX. https://www.sigsauer.com/parts/stocks.html

Hope that helps.

This message has been edited. Last edited by: MagnumU,

A picture is worth a thousand words:



You can see there's no tube there.
As stated above, there's a pic rail on the rear of the gun which allows you to attach whatever.

So if you wanted to SBR it, you'd need to buy an actual Sig stock which attaches to the pic rail.
Or I suppose you could go and buy an adapter which allows you to use a standard AR tube/stock.

No, there was another SIG brace that used to (maybe still does?) come with the Virtus pistol that was not modeled after the "minimalist" stock. It's definitely a tube variety.



I'm aware of how the SIG receiver interfaces; I have an MPX SBR. The question is, if one has this type of brace on the MCX, can you just replace the tube with a normal AR receiver extension after SBRing. This looks pretty much like the standalone folding knuckle that SIG sells with a pistol "buffer tube", but I'm not familiar enough with the braces to know since I never got into that racket.

The Virtus generation pistols only comes with the brace shown above.

The legacy MCX pistols came with a tube that approximated a buffer tube perhaps. I haven't tried to remove the brace or tube on my legacy MCX pistol.

In order to get to a buffer tube on a Virtus pistol, you could buy the $100 knuckle from SIG, then add a tube for $20+ and then add the stock of your choice. Or you could buy a Virtus SBR that has a stock that is shown on SIG's site.

Bill