'Lo noban ,
As I recall , the stack on a Rem 11 is the same as for an A-5 ;
for light loads , the ring should be against the receiver with the
flat side against the recoil spring ; for heavy loads , the ring goes between the friction collar and the recoil spring with the flat against the spring .
As the barrel recoils , for heavier loads , the concave side of the ring "squeezes" the friction collar to increase friction . Generally ,
the "drier" you can get the mag-tube and still have the gun cycle ,
the softer it will shoot . Too much oil will negate the friction collar's purpose .
Nomenclature may be off , Hawkaaa53