^that isn't normal and is probably indicative of a defect in the back-half of the action (link bar/interface with bolt carrier, interface of link bar and recoil tube, recoil spring, etc)
I've got 1500 rounds thru my first R4 Turknelli, it's running beautifully.
I like it so much I bought a second one, and will probably buy more of them, as my projects develop.
The second gun is wearing the first field prototype of my new stock assembly, the next prototype assembly may as well go onto a third gun...
These R4 Turknellis will probably get a couple thousand more rounds thru this year