Well here's a quick summary of my outing today. Hit the indoor range today so I didn't not bench test it, but from what I saw today...This upper is a definite keeper!
Shot about 600+ rds of various ammo. Mini-Mags, Rem Golden Bullets, Federal Game-Shot (710/810 Kuehl recommended), PMC Zapper, Federal Gold Medal Target's. NOT ONE problem. Fed and ate all the different ammo's without an issue. (This was right out of box..with no cleaning what so ever)
(I did try a couple of sub-sonics, but as I expected they did not cycle the bolt....BUT this is what I expected and do not count it against the upper at all.)
I have to say that as this is my favorite .22 rifle I now own.
Now for the bad news. This thing is soo much fun to shoot that I ended up getting a blister on my loading thumb from loading the mags. Time to order an M60Joe Mag loader.