Piston and rings and things
Piston rings do rotate around the ring groove during operation.
There are various reasons for this, or rather theories on why this happens.
In two stroke engines the rings are located by a pin to prevent the rotation.
It is generally accepted that the ring gaps do line up from time to time but have marginal affect on compression leakdown.
Once the rings are bedded in during the initial run in, the position of each ring gap doesn't affect oil control.
Cheers
Blackhand