Even the wife got in on it!
I'm gonna be a bit brief as the board ate my long post before I hit the button.
Bottom line: I'm impressed. I like it.
Fired 250 rounds total, a mix of Lake City M855 and Remington 55 grain. Accuracy at 25 meters was an inch or less. Grouping opened up at 100 yards when I tweaked my ACOG in, but I blame a most of that on the shooter and to a much lesser extent the wind. I know its on at 100 meters though, zeroed to the M855. I was curious to see if the 1/9 twist would have an adverse effect on the 62 grain rounds, but I don't think they're heavy enough to need 1/7.
Only malfunctions were two failures of the bolt to lock rear on an empty mag, both times with the Bushmaster stamped PMAG that came with the rifle. My other PMAG and two countdown mags were fine. I thought it might be due to pressure/movement on the mag as I was shooting at the bench and the mag was resting on a sandbag (third point of contact with the bipod for zero: whatever works right?) but I couldn't replicate it. No issues when the mag wasn't in contact with anything at all.
My other big "whoops" was the hand guard coming off on me when I was lowering the rifle after emptying a mag. Pretty sure this was user head space and timing. I'm betting the pin wasn't seated properly. I also thing the fact that I lubed that pin contributed: when I first got the rifle I was having a devil of a time removing the hand guard, but its starting to break in well now. Not quite as easy as it should be yet, but its getting there. I observed no movement of the pin for the rest of the range time, and the incident occured very early in my shooting.
Recoil is about what I expected. Wasn't light enough to doubletap a 25 meter target without a very tiny delay reacquiring the dot to center mass, but I think that with training I can lick that. Fired ten rounds with the stock folded with no problem. That is a superb feature. Military vehicle crewmen almost need that feature in my opinion. In Iraq my M4 was always on the roof of the tank with me for tactical reasons, but also because it just would have sucked to try to put that thing inside in my crew station.
Just cleaned the weapon. As expected, no carbon anywhere except the gas system. Contrary to the manual, I'm using Hoppes lube on the moving parts without issue. For the most part cleaning was wiping off old oil and reapplying. The O ring on the firing pin retaining pin is a bit obnoxious to keep it from riding up, but I'll take that over scrubbing a star chamber any day.
All in all, I'm satisfied with the purchase though my pocketbook is still reeling a bit. Most expensive tool I've ever bought. However, considering the money I put into my Bushmaster gas piston M-4 to get it where I wanted it while the ACR was what I wanted it to be out of the box, I suppose it balances out.
For good measure, two vids the wife and I took at the range.