Last time I looked DPMS was making them but looks like they've stopped.  Is anybody making new ones?

If not, then how wrong would an M4 profile barrel and an A1 upper be?

Lots of AF carbines like you describe.

There is nothing wrong with an A1 or C7 upper with a M4 cut barrel. There are lots of carbines with those out there.

If you want a C7 upper you are going to have to wait or do gun broker. WIndham was but there was an issue with the ejection port door detent cut IIRC. You can check the Windham industry forum from time to time to see the status. If you want an A1 upper look at No Dak, Brownells or Fulton Armory. The only thing hard to come by is the rear sight kit, if you shop around you can probably piece it together.

No Dak has a selection of Slick and FA.

Brownness has a A1 with forward assist.

Fulton is slick side.

Windham had the C7.

https://rguns.net/shop/r-guns-a1-forged-receiver-complete-black/

Winner!
Thanks for sharing this, I'll be ordering one tomorrow.

Also glad to hear that an a1 can go with an m4 barrel, but since a C7 Is available that's the route I'm going to take.

I was just about to post a thread asking the exact same question.

It seemed like those uppers could be found a lot of places a few years back and now they're impossible to find.

Edit: Does anyone have a source for a stripped C7 upper? I already have a bolt and dust cover.

There is a member here boywonder777, who also sells on GB.  About two years ago when I was looking for a C7 upper & other parts for a 723 build, he had them.  In the past month he sold me an A1 rear sight set.  So, he might have what you need.