Easiest solution? Go back to yoke...
Anyhow...
The larger bodied firsts (someone mentioned the HOG D1) have been the only one to give me troubles... I've never had a MK17, a MK2, or a Poseidon loosen....
Could be a design flaw...
Any other brand want to be mentioned?
@rob.mwpropane - what model(s)?
Well in the MK2's defense it was my sons tank. I can't swear that he didn't turn the reg (I'd probably bet money it was his fault). As for my personal regs I'm not sure. None of them have been rounded out though. The most annoying thing to happen is I've chewed up an o ring and had to replace it on the spot.
You can keep your yokes to yourself! (see what I did there)