My SBX (aka: Sig brace, rev 2) is currently residing on my other AR pistol, which I need to go fetch. That's how you stabilize this little bugger. It ain't fully assembled yet.
This wasn't a matched set, but rather came from opposite ends of the country in upper/lower respectively. The MML rail is fit to the upper in-house and they won't sell them separately because of refusing to allow a sloppy set to exist with their name on it. I got the upper from DSG due to some fluke in the space-time continuum (must've happened when Sam's head exploded from the troll
) where they gave me a discount deal not possible anywhere else after I returned a Rise trigger from them refusing to price match it before it had even arrived (was still in the mail when Primary Arms put it on sale), and then had to go to Michigan to find a lower to mate to it as everyone else is still out of stock from the H scare. So I got my upper for $40 less than anywhere else, and paid about $5 too much for my lower after it was shipped. I'm happy!
And then I mated the two with great anticipation: would they be loose?? Would I have the most expensive sloppy seconds AR receiver set on the planet because they couldn't be hand matched? They're not as tight as my MATEN set (which was hand matched by Mega), but that was actually stiff when it was new (like a poorly fit double barrel shotgun that takes work to get the breech open) - these aren't that tight. They're tight enough to sustain shaking hard enough to achieve the forces of Sam's head movements when someone suggests not doing a work-up to a +P+ .40 load being shot out of a glock; without pins in! They're tight!
I still have the take-up screw in the baggie it came in. There's no point in installing it.
Yes, you'll walk funny after paying the bill for the Mega's because your butt will be sore. But there's nothing else like them. I almost went with the Aero version of this configuration, but thought - for $50 bucks more I can get a Mega. I'm glad I did.