The marking on these milled lowers say Round Rock, TX (just north of Austin). Are these actually milled here in Texas or are milled by one of the major milling companies?

They don't look familiar.  But the days of only a handful of shops making all the lowers are long gone.  There are tons of shops making them now.  Some you'll never hear of because they only make them under variance for other companies to sell.  Who machined your lower never was and never will be important.  Will the company with their name on the side back their product if there's an issue, that's what's important.

Dan,
An employee of mine notified me that this thread existed, so I thought I would respond.

The lowers are made here in Round Rock.  And we will stand behind them, to address the first response to OP.  Contact us if you need anything.  Good luck with your build(I assume you're planning one if you are looking at lowers).

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From what you said, I assume you're the actual manufacturer?

I ended up purchasing a couple of these lowers from a local Dealer (Mooney's) in Round Rock. I'm very pleased with features, along with the high quality of the machine work and finish.

Here's some before pictures, I'll post more after a complete lower build in completed.

AES 1

AES 2

AES 3