I had to do a fair bit of polishing with my GSG on the rails and the interior of the frame near the muzzle to get it to cycle well with pretty much anything. That said, three boxes of 525 round blue box bulk Federal ammunition later, the pistol is still going strong without a single cleaning.
One other peculiarity I found with this pistol was the magazine springs. While I haven't clean the pistol itself, I've cleaned the magazines after each range trip. Reason being, the springs pushing up on the follower should be 6.5" long when uncompressed. However, what I was finding is that they'd "shrink", for lack of a better term", to less than 6" uncompressed. Giving them a stretch meant that feeding issues and light primer strikes. If you don't do this, then keeping the feed ramp clean is crucial. I'd rather just empty a box of ammunition and call it a day.