On all the A5's that I am aware of the friction rings had to be switched around as described for different loads. I never owned one of them, have shot a few, but as I recall the 3" 12 was supposed to be able to function with the 3 3/4DE-1oz "Express" load in a 2 3/4" shell but nothing lighter.
With too much friction applied the gun would fail to function, with not enough it would rattle your teeth.
Being used to solid breech guns I always detested the "Double Shuffle" feel of an A5 when shooting one.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra