Got the new Rainier 7.5" Pistol upper. The receivers look and fit amazing. Very happy with the purchase.
One thing I did notice is my rear Troy BUIS did not want to lay flat in the down position. I had to pull it to the left as I folded it down or else it would catch on the rail. It goes down but it's rubbing on the left side. Checked it with another upper and it didn't have the issue. Might want to keep an eye on that measurement.
This is my second Rainier upper and I wouldn't hesitate to buy another one. Top notch.