The receivers are mated by welding them together just behind the magazines. The shop I use to do the deactivations has always kept them clean, while at the same time making it not easily reversible. Too many gunsmiths go way overboard and produce terrible looking products.
So I put it's older brother next to it for some comparisons. Here are a couple of shots of the charging handle area on the EX2 and my EX1. As Enfield pointed out, the serial on the EX2 is indeed just over the 0B1700 mark.
I am also including a couple of photos of a variance between the two. The mag removal lever seems to have changed design.
As well, there is a photo of the unique (and currently useless) front sight of the EX2. There would be a metal back up sight on the rear body cover, which I suspect is part of the scope mounting assembly (which will be another holy grail...the fun does not stop).