Here's how it went:
The last piece I needed, the crowfoot wrench, came in. So...
It was time(cue ominous tones).
I know, lots of people have done this with no problem; after lucking out on the barrel, and getting everything else together, I really didn't want to screw something up. So I hauled everything out to the post vise in the back yard(more space around it, better light for pictures, and this way I can pretend there's no bloody mess in the garage).
By the way, if you're thinking of building one I highly recommend the AR15 Builder site that's run by Brownell's; pictures, video, and instructions from experts on every step.
I was able to get the use of a DPMS Claw vise block for the upper;
Upper installed and clamped.
Then slide the barrel into the upper, and install the barrel nut hand-tight.
The picture you can't see at this point is me with a torque wrench in hand thinking "Here goes." The instructions said a minimum of 35 footpounds, max of I can't remember(I'll look it back up later). I set the wrench for 35, and torqued it down. Which didn't feel that tight. At the Builder site they mentioned they generally got better accuracy closer to the minimum torque level, but I went ahead and reset the wrench to 40 and tightened the nut to that. Surprisingly easy to get this done(I know, silly statement, but I'm always happy when something I've worried about goes together that easily).
Now the gas block and tube. This is a setscrew block, when you have it in place there are two screws in the bottom you tighten against the barrel(two dimples on the barrel to match up). First you have to put the tube in the block, which is simple: slide the proper end into the block to the proper place. There's a hole through the block and one in the tube that align, then you drive in a roll pin to lock them together. Getting the pin started was a bitch, otherwise they went together no problem. Slide the block onto the barrel, guide the end of the tube into the upper, then put the block in position and tighten the screws.
Now for the handguard. This one comes with two curved wedges
that fit into the back end at the 5 and 7 o'clock positions,
If you look closely at the barrel nut, you'll see two grooves running around it. When the guard is in place there are places for two bolts to slide through the guard from the right and through the grooves. Get the bolts snugged lightly in place, make sure the rail is level with the receiver rail, then tighten them up and it locks it in place.
And that's it, the upper is done*.
The upper and lower assembled
I don't have a scale so I can't give the weight; it's heavy compared to a AR-15, but nothing horrible. And it's nicely balanced. I'm looking forward to trying it out.
Among the things learned in this:
It's not that hard.
It's bleeping amazing how many brands and styles and whatever of parts there are for these.
I have a set of roll pin punches, but if I were going to do this very often I'd get a roll pin starter punch of suitable size; getting the damn thing started was a pain without one.
*One thing missing: there's a place for a forward assist, which I hadn't planned on putting in, so I need to get one of the plugs made to fill the hole.