I find it's better to adjust the lock ring with the barrel off, get it so where it's a tight 1/4 turn to lock up. Then let the bolt slam home a couple times, take the barrel off again and you should be able to get another click or 2 on the ring, reassemble and it should be tight and not move. Once it's adjusted properly you never need to move the lock ring again. Put a little grease on the threads and shoulders of the barrel that make contact with the receiver.
I have a couple of them, biggest issue is complete tear down and degreasing all that whale oil off it, lube it up probably, reassemble and they will run forever with minimal cleaning.