I would agree Riley is not great. I would even call them "garbage". And I'm sure someone will be along to tell me I'm wrong and tell me how they've ran 60 rounds through their Riley and it's been perfect.
But how do you know it's headspace? Did you gauge it? Could also be a hundred other things. mag geometry, mag catch position, burr in the chamber, etc etc etc. It actually takes a lot more skill and quality material to produce a good AK than most people think.