What rail are you guys using with the GSG-522? Every rail I see that fits the GSG-5 says it will not fit the newer 522's.

As far as I know the GSG-522 comes with a rail pretty much built in, so the clamp on rails for the GSG-5s wouldnt be able to fit over it. It's one of the many changes that the law suit brought about.
Out of the box GSG-522 on top, GSG-5 on bottom...

I bought one, but the rail is plastic and doesnt seem too sturdy. I want to remove the plastic one and replace with a metal rail.
if you have the GSG5 without a rail system on uper receiver. i just bought mine and mine didnt come with one either.
this works great and is easily installed 2 screws. this is the one i bought:
NIB WEAVER PICATINNY RAIL CLAW SCOPE MOUNT FOR GSG-5
this the sellers name i bought from oon ebay cost me like 12.00 and works great perfict fit.
Member id legacyoutdoorsandsurvival
but there are tons of them there on ebay.
gun_nut_77