I just bought a new gsg 522sd and seen that they now rivet the extractor from the factory.Mine is a new lightweight polymer upper reciever .It is very nice.There won't be any issues with the lightweight model that I can see just because it is polymer.The bolt carrier is steel and the recoil springs and bolt ride in the carriage.The carrige snugly slides into the reciever.I think they need to revise the magazine by adding 2 or 3 small screws to the rear of the magazing so it wont separate when fully loaded.Other than that it is a kick ass little tactical 22.

Thanks for the info, my 522 lightweight carbine is on it's way.

DB