You would have to shoot a lot (many thousands of rounds), without ever switching back to 5.56, to cause clogging issues with the gas tube. The biggest problem I've had with .22lr is the crud it leaves in the lower after a few thousand rounds. Just make sure you clean the rifle very well after using .22lr and pop off some 5.56/.223 every so often (after cleaning the rifle) to blow any residue out of the gas system. Your best bet is to get a dedicated .22lr upper. Problem solved (except for having to clean your lower really well every so often).